- Email: [email protected]
Bio-economic studies on the catch of Bardawil Lagoon, North Sinai, Egypt
Egyptian Journal of Aquatic Research 45 (2019) 59–65
Contents lists available at ScienceDirect
Egyptian Journal of Aquatic Research journal homepage: www.sciencedirect.com/locate/ejar
Full length article
Bio-economic studies on the catch of Bardawil Lagoon, North Sinai, Egypt Attia A.O. El-Aiatt, Kariman A.Sh. Shalloof ⇑, M.M. Saber Fisheries Division, National Institute of Oceanography and Fisheries, Egypt
a r t i c l e
i n f o
Article history: Received 30 October 2018 Revised 28 February 2019 Accepted 5 March 2019 Available online 18 March 2019 Keywords: Bardawil Lagoon Egypt Lm Lc Biomass Income Bycatch
a b s t r a c t The paper aims to give a comprehensive descriptive survey on the production of Lake Bardawil from 1985 to 2015. The average production in this period was 2970 tons. Monthly samples were collected for 12 species of fish during fishing season 2015. The results showed that the Length at first capture (Lc) of different species in Bardawil Lagoon was less than the length at first maturity (Lm); Lm of Mugil cephalus, Sparus aurata and Dicentrarchus labrax was 31.1, 24.5 and 31.0 cm, meanwhile, Lc was 29.0, 18.5 and 27.8 cm respectively. The percentage of small fish with less than the Length at first maturity (Lm) constitutes 67.3% for inexpensive species and 77.05% for expensive species. The loss of biomass in the inexpensive species was estimated at 3268 tons and the loss in income was 199 million Egyptian pounds (LE). The loss of biomass of expensive species was calculated at 1455 tons and the loss of income was 175 million LE. The total loss of biomass was 4723 tons and 374 million LE due to fishing violations and the use of illegal nets in only one fishing season. For proper management, the Length at first capture (Lc) must be increased by widening the nets mesh size. Legal fishing methods and the development of appropriate non-traditional methods for the management of Bardawil Lagoon must be applied. Ó 2019 National Institute of Oceanography and Fisheries. Hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Introduction Lake Bardawil is considered one of the most economic water masses because of its high-quality fish production, which is exported to Europe, as well as its non-polluted habitat. This lake does not suffer from the deterioration of fish quality and fish products like other Egyptian lakes (El-Halag et al., 2013). Bardawil Lagoon’s production is amounted to 2500–3000 tons of fish composed of 50% sea bream, 45% mullets and 5% miscellaneous (Fouda et al., 1985). Seven species (sea bream, sea bass, grey mullet, common sole, Egyptian sole, thin lip grey mullet and shrimp) are targeted in the lagoon while more than 20 species and two threatened ones (turtle and seahorse) are caught as bycatch (Mehanna et al., 2011). In 2014 the sea bream, sea bass, solea, shrimp and crab were represented by about 8.3%, 1.7%, 5.3%, 22.6%, and 18.8% respectively (GAFRD, 2014). About 5000 local fishermen are working in the lagoon using different kinds of fishing gears; some of them are very harmful to the
Peer review under responsibility of National Institute of Oceanography and Fisheries. ⇑ Corresponding author at: Fisheries Division, Fisheries Biology Lab., National Institute of Oceanography and Fisheries, Egypt. E-mail address: [email protected] (K.A.Sh. Shalloof).
lagoon’s fisheries. In 1990, 786 fishing boats that used the Dabba method (trammel net) were operating in the lagoon. They represented about 81.5% of the total fishing licenses that worked in Bardawil Lagoon (Ameran, 2004). Breikaa (1997) recorded two main fishing methods that are used in Bardawil Lagoon, namely Dabba and Bouss (Veranda or aerial traps) methods. Dabba fishing method contributed by 847 fishing boats during 1996; about 79% of the fishing fleet of which each fishing boat reached about 6 m in length, 1.8 m in width and with 6–25/HP outboard motor. Salem and El-Aiatt (2012) stated that the shrimp fisheries were caught by small trawlers, and increased rapidly since 1995 with the development of the shrimp biomass in the lagoon. Salem and El-Aiatt (2013) described the trammel small boats in Bardawil Lagoon; 6 m in length and powered by 9.9/HP outboard motor. On the other hand, Crespi (2002) illustrated that mullet species (Mugil spp., Liza spp.), common sole, Solea solea (L.), sea bass, D. labrax (L.) and the common cuttlefish were the major target species for the gill and trammel nets. Gianna (1994) recorded the targeted species of trammel net in the Adriatic Sea and Tyrrhenian Sea: the striped sea bream (Lithognathus mormyrus), red mullet (Mullus barbatus), blotched picarel (Spicara flexuosa), common sole (Solea solea), tub gurnard (Trigla lucerna) and common cuttlefish (Sepia officinalis).
https://doi.org/10.1016/j.ejar.2019.03.001 1687-4285/Ó 2019 National Institute of Oceanography and Fisheries. Hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
60
A.A.O. El-Aiatt et al. / Egyptian Journal of Aquatic Research 45 (2019) 59–65
Besides, crab gill nets are mostly suitable for collecting crab species, as they have less impact on the sea grass ecosystem than trawl or push nets. Collapsible crab traps are not suitable because bait does not attract berried female crabs (Xiao and Kumar, 2004). Also, Nitiratsuwan (2009) reported that crab gill nets caught more berried crabs than collapsible crab traps. Moreover, Mehanna et al. (2011) studied the effects of shrimp bottom trawling on the Bardawil Lagoon fisheries and showed that a trawler operating in Bardawil Lagoon lands about 66 kg of bycatch per two boats per day, on average. Some of the bycatch may include rabbit fish, sparid species, sardine, eel and small groupers. For this landed part of the bycatch, the price does not exceed 5 LE per kg. Also, they reported that bycatches are generally uncontrolled and may pose a risk to the assortment of the species that are facing extinction while causing deterioration to the health of the ecosystem. In addition, bottom trawling also affects the ecosystem by its physical impact on sea beds and bottom habitats. Furthermore, Mehanna (2006a, 2006b) mentioned that the serious change in catch composition during the last 20 years in Lake Bardawil can be referred to the change in the ecological conditions of the lake, uncontrolled fish exporting policy and the overexploitation since the late 80’s until now. These factors lead to the decreasing of sea bream and sea bass production. The predomination of crustacean species led to the introduction of the Kalsa fishing method (trawl nets). This fishing technique was destructive as it contributed to the catching of fish fry, especially bottom feeder like sea bream and sea bass, as well as the progressive decline and collapse of their stocks. The present work describes the negative impact of the irregularity of the used fishing methods, as well as the effect of catching small-sized fish before reaching sexual maturity in Bardawil Lake. Also, it aims to give information on the loss in biomass and income resulting from these irregularities. Material and methods Area of study The study was carried out in Bardawil Lagoon (Fig. 1); situated in the north of Sinai Peninsula. The fundamental contacts between the Mediterranean Sea and the lake are via two man-made canals; the Western Canal (Boughaz I) and the Eastern Canal (Boughaz II). There is additionally a third narrow natural boughaz referred to as El-Zaranik at the eastern edge of the lagoon. The lagoon is overly shallow and the water levels never surpass three meters in depth
(El-Halag et al., 2013). The water exchange between the lagoon and the Mediterranean Sea through the inlets plays a significant function in the water salinity standard (Abd Ellah and Hussein, 2009). It should be noted that the fish production of Bardawil Lagoon during the period from 1985 to 2015 was obtained from the statistics year book of GAFRD (General Authority for Fish Resources Development). Catch evaluation Monthly random samples were collected from three landing sites, El-Nasr, Oghzoan and El-Telol port, as shown in Fig. 1, during fishing season 2015, from April 2015 to January 2016. The following data were estimated: 1. The total number of fish samples for each species collected. 2. Length-weight relationship (was demonstrated by the potential equation (W = a Lb, Ricker, 1975), where W is the total weight (g), and L is the total length (cm). 3. The Length at first capture Lc. 4. The Length at first maturity (Lm) gathered from published papers for each species in the same area or nearby areas (Table 1). 5. The number of fish with lengths less than Lm 6. The percentage of fish with lengths less than Lm = (number of fish sample less than Lm)/(total sample) * 100. 7. The catch from fish less than Lm (Tons) = % of fish with length less than Lm total catch for all species. 8. The weight at first maturity Wm = a Lbm Where a and b are constants of length-weight relationship W = a Lb 9. The average weight for fish smaller than length at first maturity (w). 10. The natural mortality (M) can be computed by the following equation: M = (w)( 1/3), where w is the mean fish weights for fish smaller than Lm (Ursin, 1967). 11. The equation that describes the loss of biomass as a result of fishing small fish, is as follows: QA = [(1000/w) * Wm]/(1000) (1 M) (Najmudeen and Sathiadhas, 2008) where: QA = Adult fish magnitude congruent to 1 kg of small fish after a cycle of (t) years. Wm = weight of the fish at the Length at first maturity after a period of (t) years. w = Average weight for fish smaller than the Length at first maturity. 12. Losses of biomass = output of the previous equation the product from the small fish of each species.
Fig. 1. Bardawil Lagoon; area of study showing Landing sites.
A.A.O. El-Aiatt et al. / Egyptian Journal of Aquatic Research 45 (2019) 59–65 Table 1 Length at first maturity (Lm) and average annual prices. Fish species
Lm (cm)
Reference
Price (LE 1000/ton)
Mugil cephalus Sparus aurata Portunus pelagicus Siganus rivulatus Terapon puta Penaeus semisulcatus Epinephelus aeneus Solea vulgaris Liza ramada Liza aurata Hemiramphus far Dicentrarchus labrax
31.1 24.5 10.2 14.4 13.2 5.8 47.1 19.1 28.7 23.1 23.1 31.0
El-Aiatt (2013) Mehanna (2007) Emam, (2010) Kabil (2015) kassem (2017) Ameran (2004) Rafail et al. (1969) Shokry (2013) Mehanna (2006a, 2006b) Mehanna (2006a, 2006b) Mahmoud (in press) Salem (2004)
50 150 80 40 25 100 250 120 40 40 40 100
13. Losses of income = Losses of biomass average price. Results and discussion The Bardawil Lagoon has experienced many problems, which might lead to environmental breakdown, insufficiency of fish catch and radical changes in its ecosystem. The drying up of some regions within the lagoon and subsequently loss of its biological and economic magnitude is due to the repeated changes of inward shape and dimension of the lake (Abd Ellah and Hussein, 2009). As shown in Fig. 2, the development of the total catch production peaked during 2009 and was the lowest in 1992. This may have been affected by the number of fishing boats, the number of fishermen and environmental conditions. The closure of the boughaz, connecting the lagoon with the Mediterranean during sea rises, imposes the danger of drying up the lagoon and the subsequent loss of its biological and economic value. Moreover, an extensive salt production system; constructed in the eastern part of the lagoon; leads also to considerable ecological changes. Furthermore, there is an increasing pressure to establish touristic developments along the lake’s shores (Mageed, 2006). From Table 2 and Fig. 2, species composition of the catch of Bardawil Lagoon, during the period from 1985 to 2015, was Portunus pelagicus, Penaeus semisulcatus, Mugil cephalus, Sparus aurata, Liza ramada, Liza aurata, Solea solea, Dicentrarchus labrax, Signus rivulatus, Terapon puta, Hemiramphus far, Epinephelus aeneus and others. Ben-Tuvia (1975) listed about 60 species of fishes gathered from the lagoon during the 1970s, but Khalil et al. (2002) listed up to 44 species only from Bardawil Lagoon. On the other hand, Mehanna (2006a, 2006b) reported that the total annual commercial landings of Bardawil Lagoon varied between 2226 and 5410 tons (1998–2011) earning almost 96 million LE. She also mentioned that the catch of Bardawil Lagoon is composed mostly of M. cephalus, L. ramada and L. aurata (family: Mugilidae); S. aurata (Sparidae) D. labrax and D. punctatus (Moronidae); Solea spp. (Soleidae); A. regius (Sciaenidae); Epinephelus spp. (Serranidae), and Siganus spp. (Siganidae) as well as crustacean species that
61
are represented in the catch by shrimps; mainly Metapenaeus stebbingi; and crabs; mainly P. pelagicus. The author also pointed out that the common commercial fishes of Bardawil Lagoon are the gilthead sea bream (S. aurata), grey mullets (Mugilidae), the sea bass (D. labrax) and the common sole (Solea solea). In the present study, the average total catch of Bardawil Lagoon during the period from 1985 to 2015 was 2970 tons. In India, Kumar et al. (2013) recorded that about 76% of the bycatch weight was gathered from crab gill net. This was supported by Fazrul et al. (2015) who reported that 50.8% of the bycatch was also entangled by crab gill net. The three most principal bycatch species were horseshoe crab (Carcinoscorpius rotundicauda), mud crab (Scylla serrata) and spotted catfish (Arius maculates). Although crab gill net was designed as selective fishing gear, it still captures many non-target species or bycatch. So, in order to manage marine fisheries effectively, the problem of bycatch must be assessed and managed (Alverson et al., 1994). The average catch from the crabs was 662 tons in the period from 1985 to 2015; representing 22.3% of the total yield. Shrimp was the second important catch in the yield; representing 18.2% of the total yield. It was followed by mullet with an average catch of 441 tons in the period from 1985 to 2015, which amounted to 14.8% of the total yield, followed by sea bream with an average catch of 434 tons, which amounted to 14.6% of the total yield. Liza ramada ranked in the 5th rank of catch production, since its average catch was 294 tons and amounted to 9.9% of the total yield. Liza aurta, Solea solea, Dicentrarchus labrax, Terapon puta and Siganus rivulatus were represented by 7.2, 4.9, 2.2, 1.5 and 1.4% of the total yield respectively. Hemiramphus far and Epinephelus aeneus represented 0.7% and 0.5%, respectively of the total yield production (Table 2). Table 3 and Fig. 3 summarize the catch composition during fishing season 2015 in Bardawil Lagoon. Also, the result shows that more than 12 species weighing 4704 tons were caught by different fishing methods. Sadek and Ameran (1984) reported that the catch of Bardawil Lagoon was composed mainly of the gilthead sea bream, with an average yield of about 48.49% of the total catch. The collapse in the production of sea bream in fishing season 2015 may be attributed to the difference in the ecological conditions and also the use of illegal fishing gears. Abd Ellah and Hussein (2009) concluded that the majority of the lagoon is frequently hyper saline. Ben-Tuvia (1979) mentioned that the abnormally high salinities prevent both the adult and the young fish from settling in the lagoon. In the present study, the catch composition of Bardawil Lagoon was mainly dominated by crustaceans (crabs and shrimps). These results agree with other studies obtained by Mehanna (2006a, 2006b). She mentioned that crustaceans’ (shrimps and crabs) production has been extremely elevated in the lagoon, going up to 60% of the total catch in 2005, affecting the catch of extra commercial fish species like sea bream and sea bass. Also she mentioned that the appearance of crustacean species led to the introduction of a new fishing technique called the Kalsa fishing technique or
Fig. 2. Annual catch of Bardawil Lagoon (1985–2015).
62
A.A.O. El-Aiatt et al. / Egyptian Journal of Aquatic Research 45 (2019) 59–65
Table 2 The Annual variation in the total fish yield and species composition of the Bardawil Lagoon from 1985 to 2015 (GAFRD, 2016). Years
S. aurata
D. labrax
S. solea
E. aeneus
A. regius
M. cephalus
L. ramada
L. aurata
P. semisulcatus
P. pelagicus
T. puta
H. far
S. rivulatus
A. anguilla
Others
Total
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 average %
1418 1303 1027 1022 952 977 956 280 274 76 110 146 176 228 139 253 223 266 279 339 293 274 303 336 315 304 214 256 240 230 239 434 14.6
135 84 83 94 157 186 157 58 40 59 10 26 71 43 43 31 57 25 40 27 35 44 69 90 81 46 28 45 40 47 56 65 2.2
130 42 70 101 94 136 133 62 118 57 79 149 139 134 165 149 142 140 159 127 168 292 281 343 232 123 194 159 122 147 170 147 4.9
11 42 17 8 12 20 22 9 3 6 4 11 11 14 9 10 11 9 6 9 13 22 13 28 28 25 2 7 10 19 21 14 0.5
2 11 5 2 2 2 1 1 1 1 1 2 1 0 0 3 0 3 3 3 3 5 3 4 4 5 4 6 7 7 9 3 0.1
153 199 122 163 211 284 141 151 163 213 361 466 422 422 510 524 578 651 600 366 405 480 576 851 748 606 739 659 379 555 962 441 14.8
126 182 329 193 170 214 168 180 373 206 339 393 272 337 320 347 330 350 318 258 269 268 301 347 308 444 374 353 281 298 469 294 9.9
72 101 158 395 459 910 882 559 697 660 104 58 85 90 76 82 81 81 82 79 79 76 74 100 76 83 78 74 74 74 161 215 7.2
0 0 0 0 0 0 0 0 0 2 274 76 288 271 576 787 595 814 808 329 775 1264 1569 1428 1355 1221 1176 1099 1149 624 302 541 18.2
0 0 20 25 31 26 13 70 89 206 492 99 507 552 658 754 520 609 953 570 1322 1184 1343 1611 2053 1457 1201 929 734 519 1973 662 22.3
0 0 0 0 0 0 0 0 0 0 0 0 0 71 76 62 51 50 32 71 102 83 80 89 33 52 84 108 87 147 65 43 1.5
0 0 0 0 0 0 0 0 0 0 0 0 0 37 45 12 18 14 6 9 12 29 19 24 72 103 87 43 32 23 49 20 0.7
0 0 0 0 0 0 0 0 0 0 0 0 0 60 108 55 169 46 5 9 19 49 19 69 61 212 305 51 8 19 49 42 1.4
0 0 0 0 0 0 0 0 0 0 0 0 0 3 5 47 10 10 14 12 15 35 26 35 30 26 12 16 18 15 21 11 0.4
4 6 48 19 12 6 0 0 52 14 59 109 157 15 28 28 17 14 20 18 24 37 51 38 16 27 29 40 56 35 158 37 1.2
2051 1972 1878 2023 2100 2762 2473 1371 1810 1500 1832 1536 2128 2277 2758 3145 2801 3082 3326 2227 3534 4142 4729 5393 5410 4733 4529 3845 3237 2758 4704 2970 100.0
Table 3 Total catches and species composition from Bardawil Lagoon during season 2015. Fish species
Catch (Tons)
% of total catch
Total Number of the sample
Number of the sample of small fish
% of small fish
Total catch of small fish (Tons)
Sparus aurata Dicentrarchus labrax Penaeus semisulcatus Epinephelus aeneus Solea solea Portunus pelagicus Mugil cephalus Liza ramada Liza aurata Siganus rivulatus Terapon puta Hemiramphus far Others Total
239 56 302 30 170 1973 962 469 161 49 65 49 179 4704
5.08 1.19 6.42 0.64 3.61 41.94 20.45 9.97 3.42 1.04 1.38 1.04 3.81
1630 1269 939 509 2142 2147 1931 1567 160 2722 3424 976
1350 918 921 505 1313 1348 1291 1382 157 1794 2205 528
83 72 98 99 61 63 67 88 98 66 64 54
198 41 296 30 104 1239 643 414 158 32 42 27
19,416
13,712
70.6
trawl nets. This fishing method was very destructive, and contributed to catching fish fry of bottom feeders, like soles, sea bream and sea bass, resulting in the progressive decline of their stocks. The Length at first capture (Lc) of different species in Bardawil Lagoon was less than the length at first maturity (Lm). The Lm of M. cephalus, S. aurata and D. labrax was 31.1, 24.5 and 31.0 cm, meanwhile, Lc = 29.0, 18.5 and 27.8 cm for the previous species respectively (Tables 1 and 4). Table 3 summarizes the catch composition of small fish (less than the Length at first maturity). Also this table represents the negative impact of the presence of small fish of the inexpensive species (P. pelagicus, M. cephalus, L. ramada, L. aurata, S. rivulatus,
T. puta and H. far) in the catch of boats, as a result of using illegal fishing nets. Generally the percentage of small fish from inexpensive and expensive fish amounted to 70.6% (total sample was 19,416 and total sample from small fish was 13,712) (Table 3). While, the percentage of small fish of inexpensive species with length less than the Length at first maturity (Lm) was 67.3%, (total sample 12,927 and total small fish sample 8705). One of the basic regulations for the sustainability of the fish community is to allow the fish to spawn at least once before fishing. Hence, the minimum legal size of fish must be greater than the Length at first maturity (Öztekin, 2007). As shown in Table 3 the samples that were collected from the production of expensive species include Sparus aurata, Dicentrarchus
63
A.A.O. El-Aiatt et al. / Egyptian Journal of Aquatic Research 45 (2019) 59–65
Fig. 3. Species composition during fishing season 2015 in Bardawil Lagoon.
Table 4 Different biological parameters for local species in Bardawil Lagoon during 2015. Items
P. pelagicus
M. cephalus
L. Ramada
L. aurata
S. rivulatus
T. puta
H. far
S. aurata
D. labrax
P. semisulcatus
E. aeneus
S. solea
Length at the first capture Lc Average weight of fish under Lm50 (w) Constant formula of L-W relationship (a) Constant formula of L-W relationship (b)
9.5 45.4
29 217.0
23.7 103.1
17 40.9
13.5 18.3
12.6 17.2
22.6 58.5
18.5 91.9
27.8 184.2
2.4 5.2
34 470.7
17.7 50.0
0.0479
0.0097
0.0072
0.0114
0.0072
0.0106
0.0042
0.0186
0.0165
0.1605
0.0191
0.0136
3.1825
3.0219
3.0378
2.8805
3.0907
3.0004
3.1046
2.909
2.8444
2.9601
2.8695
2.9206
Fig. 4. Total biomass loss (ton) from inexpensive species caught by different fishing gears during 2015.
Fig. 5. Total income loss (million LE) of inexpensive species caught by different fishing gears during 2015.
labrax, Penaeus semisulcatus, Epinephelus aeneus and Solea solea. The classification depends on the Length at first maturity (Lm); 1 – small fish less than Lm, 2 – mature fish from Lm and greater than Lm. The proportion of small fish represents 77.05% of the production (total sample 6498 and total small fish sample 5007). This means that, the percentage of small fish with a length less than the Length at first
maturity (Lm) constitutes 67.3% for inexpensive species and 77.05% for expensive species. This may be due to using illegal fishing methods in the lagoon. The presence of small fishes more than 50% indicates an overfishing process in the lagoon. It is worth mentioning that there are two main fishing methods that are certified to operate in Bardawil Lagoon; namely Dabba and
64
A.A.O. El-Aiatt et al. / Egyptian Journal of Aquatic Research 45 (2019) 59–65
Fig. 6. Total biomass loss (ton) of expensive species caught by different fishing gears during 2015.
Fig. 7. Total income loss (million LE) of expensive species caught by different fishing gears during 2015.
Bouss methods. Other illegal fishing gears that operate in the lagoon are namely Dahbana, Kalsa (trawl net), Sinnar (long line), Cioncholla (looks like Dahbana); beside the crabs’ gear ‘‘Isfinkes gear” (Mehanna, 2006a, 2006b). In order to protect fish stock and to enable them to participate at least once in reproduction, several measures should be taken into consideration such as an urgent increase in the mesh size of the already used nets as well as the evaluation of all fishing methods in the lagoon and prohibiting the dangerous ones. The bycatches influence on the ecosystem as they increase the mortality of the incidentally captured species and have a negative economic impact when they consist of the juveniles of the commercially important species as well as other fish used as live food; hence, they are considered as a hazard to food security and viable fisheries (FAO, 2014). Jomaa (2018) found a negative impact of the purse – seine, trammel net and trawl net on the Mediterranean catch off the Sinai coast. He found that the percentage of small fish was 55% of the catch of the purse–seine, 27.5% of the catch of the trammel net and 42.2% of the trawl net. The negative impact on the biomass was 923.2, 1061.7 and 160.8 tons for each of the purse–seine, trammel net and trawl net respectively, with a total of 2145.4 tons in one fishing season of 2016 amounting to 212 million Egyptian pounds. In the present study, the loss in biomass of inexpensive species was estimated as 3268 tons and the loss in income was 199 million LE. The loss in biomass of expensive species was calculated as 1455 tons and the loss of income was 175 million LE. The total loss in biomass was 4723 tons and 374 million LE due to unlawful fishing methods and the use of illegal nets in one fishing season. Salem et al (2018) found that the landing of small fish has led to more losses of stock biomass, which formed about 345 tons and about
23.6 million LE losses in income in one fishing season, 2016 in Bardawil Lagoon. The current results indicated that the landing of small fish from inexpensive species leads to more losses of stock biomass, which formed 1525, 777.3, 609.8, 265.1, 29.9, 36.4 and 24.2 tons for Portunus pelagicus, Mugil cephalus, Liza ramada, Liza aurata, Siganus rivulatus, Terapon puta and Hemiramphus far respectively (total loss biomass = 3268 ton), and 199 million LE losses in income in one fishing season, 2015; 122.0, 38.9, 24.4, 10.6, 1.2, 0.9 and 1.0 million LE for P. pelagicus, M. cephalus, L. ramada, L. aurata, S. rivulatus, T. puta and H. far respectively (Figs. 4 and 5). It has been found that the landing of small fish from expensive species leads to more losses of stock biomass, which formed 343, 52, 705, 67 and 114 tons for S. aurata, D. labrax, P. semisulcatus, groupers E. aeneus and sole S. solea, respectively (total loss biomass = 1455 ton), and 175 million LE losses in income in one fishing season, 2015; 51.4, 5.2, 71, 16.6 and 13.6 million LE for S. aurata, D. labrax, P. semisulcatus, E. aeneus and S. solea respectively, as shown in Figs. 6 and 7. Gaber (2012) reported that the losses in biomass in crabs, P. pelagicus 371 tons; shrimp 353 tons; groupers, E. aeneus 398 tons; Rabbit fish, Solea spp 148.2 tons; and Snapper, T. puta 82.8 tons in the Mediterranean coast of Sinai, during 2010. Jomaa (2018) reported the losses in biomass in groupers E. aeneus = 181 tons; crabs P. pelagicus = 512 tons; shrimp P. semisulcatus = 25 tons; mullet M. cephalus = 64.6 tons; sea bream S. aurata = 6.6 tons; rabbit fish = S. rivulatus 61.8 tons; and snapper = T. puta 10.3 tons in the Mediterranean coast of Sinai, during 2016. Also Salem et al (2018) recorded the losses in biomass of several species such as thin lip grey-mullet L. ramada = 132.8 tons; grey-mullet M. cephalus = 116.6 tons; sea bream S. aurata = 68.3 tons; sole (S. solea) = 7.4 tons; sea bass D. labrax = 7.4 tons; and crabs P. pelagicus = 13.1 tons from using gill net in Bardawil Lagoon during 2016.
A.A.O. El-Aiatt et al. / Egyptian Journal of Aquatic Research 45 (2019) 59–65
Conclusion This study gives a comprehensive descriptive survey of the production in Lake Bardawil from 1985 to 2015. The development of the total catch production peaked during 2009 and was the lowest in 1992. The percentage of small fish with a length less than the Length at first maturity (Lm) constitutes more than 50% for inexpensive and expensive species indicating an overfishing process in the lagoon. The total loss in biomass was 4723 tons and 374 million LE due to unlawful fishing methods. For better-informed management decisions, the Length at first capture (Lc) must be increased by enlarging the size of the mesh of the fishing nets. We also recommend the prohibition of the destructive gears like ‘‘Kalsa” and other illegal nets. More investigations are needed based on the biology of the economic fishes in Bardawil Lagoon and gear selectivity of different nets to manage and protect this vital resource.
References Abd Ellah, Radwan G., Hussein, Maged M., 2009. Physical limnology of Bardawil Lagoon, Egypt. American-Eurasian J. Agric. Environ. Sci. 5 (3), 331–336. Alverson, D.L., Freeberg, M.H., Murawski, S.A., Pope, J.G., 1994. A Global Assessment of Fisheries Bycatch and Discards, FAO Fish. Tech. Paper 339. FAO, Rome, p. 233. Ameran, M.A.A., 2004. Studies on the Crustacean Fishery in Bardawil Lagoon (Ph.D. Thesis). Faculty of Environmental Agricultural Science, Suez Canal Univ, AlArish. Ben-Tuvia, A., 1975. Comparison of the fish fauna in the Bardawil Lagoon and the Bitter Lakes. Rapp. Commun. Int. Mer Médit. 23 (3), 125–126. Ben-Tuvia, A., Golani, D., 1979. Ten years of fisheries biology investigations of the Bardawil Lagoon. Fish. Fish Breed. Israel 14 (2), 29–37 (in Hebrew with English abstr). Breikaa, M.I.M., 1997. Fisheries management on the Bardwell Lagoon, Northern Sinai, Egypt. J. Aquat. Biol. Fish 1 (2), 291–307. Crespi, V.M., 2002. Recent evolution of the fishing exploitation in the Thau lagoon, France. Fish. Manage. Ecol. 9 (19), 29. El-Aiatt, A.A.O., 2013. Biological Studies on Family Mugiliadae in Bardawil Lagoon (M.SC. Thesis). Fac. Agriculture, Suez Canal University. El-Halag, Rabie S.F., Shaker, Ibrahim M., Mehanna, Sahar F., Othman, Mohammed F., Farouk, Alam El-Deen, 2013. Impact of some environmental condition on water quality and some heavy metals in water from Bardawil Lake. New York Sci. J. 6 (11), 5–13. Emam, W.W.M., 2010. Ecological and Population Dynamic Studies on Some Crab Species in Bardawil Lagoon, Egypt (MSc Thesis). Zoology Department, Faculty of Science, Ain Shams University. FAO, 2014. In: The State of World Fisheries and Aquaculture 2014. FAO fisheries Technical Paper, Rome, p. 223. Fazrul, H., Hajisamae, S., Ikhwanuddin, M., Pradit, S., 2015. Assessing Impact of Crab gill net Fishery to Bycatch Population in the Lower Gulf of Thailand. Turk. J. Fish. Aquat. Sci. 15, 761–771. Fouda, M.F., Wanas, M.K., Saleh, M.A., 1985. Ecology of Bardwell Lagoon, A Report to the Oil Pollution Research Unit, Pembroke. UK for BP Petroleum LTD, Egypt. Gaber, M., 2012. Studies on Fish Production of Mediterranean Coast in North Sinai Governorate (Ph.D. Thesis). Faculty of Agricultural at Cairo, EL-Azhar University. GAFRD, 2014. Report of General Authority for Fish Resources Development on Egyptian Fishery. GAFRD, 2016. Annual Fishery Statistics Report, General Authority for Fish Resources Development (GAFRD). Ministry of Agriculture, Cairo, Egypt. Gianna, F., 1994. Trammel and Gill-nets Selectivity in the Adriatic Sea and Tyrrhenian Sea. Participating Institutions: Consiglio Nazionale delle Richerche (CNR), Istituto di Ricerche Sulla Pesca Marittima (IRPEM), 60125 Ancona, Italy.
65
Jomaa, S.M.S., 2018. Studies on Traditional Characters of the Fishing of Eastern Mediterranean (North Sinai Coast) (M.Sc. Thesis). Fac. Agriculture, Arish University. Kabil, S.M.A., 2015. Studies on Biological and Dynamics of Siganidae Family in the Bardawil Lagoon (M.Sc. in Environmental Agricultural Sciences). Suez Canal University. Kassem, S., 2017. Biological and Dynamical Studies on the Small Scaled terapon Stock (Family: Terapontidae) in Bardawil Lagoon (M.Sc. Thesis). Faculty of Environmental Agricultural Sciences, Arish University, Egypt. Khalil, M.T., El-Ganainy, A.A., Yassien, M.M., 2002. Ecological Survey of Bardawil Nature Protectorate; Fishes and Fisheries, MedWetCoast project. EEAA, Egypt. Kumar, A., Sundaramoorthy, B., Jakhar, J.K., 2013. Standardization of crab bottom set Gillnet for reduction of Bycatch at Thoothukudi coast, Tamilnadu, India. Arch. Appl. Sci. Res. 5, 74–81. Mahmoud, H.S., in press. Biological and Dynamical Studies on the Garfish (Family: Belonidae) in Bardawil Lagoon (MSc Thesis). Fac. Env. Agric. Sci. Arish Univ. ELArish, North Sinai. Mageed, A.A., 2006. Spatio-temporal variations of zooplankton community in the hypersaline lagoon of Bardawil, North Sinai – Egypt. Egypt J. Aquat. Res. 32 (1), 168–183. Mehanna, S., 2006a. Fishes and fisheries. In: Khalil, M., Shaltout, K. (Eds.), Lake Bardawil and Zaranik Protected Area. Publication of National biodiversity unit, 15 (Chapter 9). Mehanna, S., 2006b. Lake Bardawil fisheries: current status and future sight. J. Egypt Ger. Soc. Zool. 51 (D), 91–105. Mehanna, S.F., 2007. Stock assessment and management of the Egyptian sole Solea aegyptiaca Chabanaud, 1927 (Osteichthyes: Soleidae), in the Southeastern Mediterranean, Egypt. Turk. J. Zool. 31, 379–388. Mehanna, S., El-Aiatt, A., Salem, M., 2011. An investigation of the impacts of shrimp bottom trawling on the Bardawil Lagoon fisheries, Egypt (Egyptian J. of Aquatic Biology and Fisheries. 15, (3). ISSN 1110 – 6131). In: 4th International conference on Fisheries and Aquaculture, 3-5 October, Cairo, Egypt, pp. 407– 416. Najmudeen, T.M., Sathiadhas, R., 2008. Economic impact of juvenile fishing in a tropical multi-gear fishery. Fish Res. 92 (2), 322–332. Nitiratsuwan, T., 2009. ‘‘Sustainable fisheries management for the blue swimming crab (Portunus pelagicus Linnaeus, 1758) in Trang province”. Area Based Dev. Res. J. 1, 28–42. Öztekin, A., 2007. Sarpa (Sarpa salpa L.1758) balıg˘ı avcılıg˘ında kullanılan sade alamana ag˘larının seçicilig˘i. Çanakkale onsekiz mart Üniversitesi Fen Bilimleri Enstitüsü, Yüksek Lisans Tezi, 28s, Çanakkale. Rafail, S.Z., Daoud, W.L., Hilal, M.M., 1969. Long line Mediterranean fisheries studies west of Alexandria. Stud. Rev. Gen. Fish. Counc. Mediterr. 42, 3–16. Ricker, W.E., 1975. Computation and interpretation of biological statistics of fish populations. J. Fish. Res. Board Can. 191, 1–367. Sadek, S., Ameran, M.A.A., 1984. Bardawil LAGOON Fish Development Resources for the Period 1979/83. GAFRD, Cairo, Egypt, p. 170. Salem, A.A., Reyad, I.R., El Aiatt, A.A.O., Gaber, M., Rahnda, E.M., Rana, E.M., 2018. Biological and economical evaluation of bycatch and discards of fisheries for gill net in Bardawil Lagoon. J. Egypt. Acad. Soc. Environ. Dev. 19 (1), 107–116. Salem, M., 2004. Biological Studies for the Fishery Regulation and management of the Bardawil Lagoon (Ph.D. Thesis). Fac. Env. Agric. Sci. Suez Canal Univ, ElArish, North Sinai, Egypt. Salem, M., El-Aiatt, A., 2013. Improvement of trammel net landing and reduction of fishing for gilthead sea bream, Sparus aurata juveniles in Bardawil Lagoon, North Sinai, Egypt. J. Anim. Poultry Fish Prod. Suez Canal Univ. 1. Salem, M., El-Aiatt, A., 2012. Population dynamics and fisheries management of Penaeus semisulcatus exploited by shrimp trawl of Bardawil Lagoon, North Sinai, Egypt. Egypt. J. Anim. Prod. 49 (Suppl. Issue), 185–191. Shokry, S.M., 2013. Fisheries Characteristics and Population dynamics of Commercial Species of Family Soleidae in Bardawil Lagoon, North Sinai, Egypt (M.Sc. Fac. Sci.). Suez Canal Univ.. Ursin, E., 1967. A mathematical model of some aspects of fish growth, respiration and mortality. J. Fish. Res. Board Can. 24, 2355–2453. Xiao, Y.S., Kumar, M., 2004. Sex ratio, and probability of sexual maturity of females at size of the blue swimmer crab, Portunus pelagicus (Linneaus), off Southern Australia. Fish. Res. 68, 271–282.
Contents lists available at ScienceDirect
Egyptian Journal of Aquatic Research journal homepage: www.sciencedirect.com/locate/ejar
Full length article
Bio-economic studies on the catch of Bardawil Lagoon, North Sinai, Egypt Attia A.O. El-Aiatt, Kariman A.Sh. Shalloof ⇑, M.M. Saber Fisheries Division, National Institute of Oceanography and Fisheries, Egypt
a r t i c l e
i n f o
Article history: Received 30 October 2018 Revised 28 February 2019 Accepted 5 March 2019 Available online 18 March 2019 Keywords: Bardawil Lagoon Egypt Lm Lc Biomass Income Bycatch
a b s t r a c t The paper aims to give a comprehensive descriptive survey on the production of Lake Bardawil from 1985 to 2015. The average production in this period was 2970 tons. Monthly samples were collected for 12 species of fish during fishing season 2015. The results showed that the Length at first capture (Lc) of different species in Bardawil Lagoon was less than the length at first maturity (Lm); Lm of Mugil cephalus, Sparus aurata and Dicentrarchus labrax was 31.1, 24.5 and 31.0 cm, meanwhile, Lc was 29.0, 18.5 and 27.8 cm respectively. The percentage of small fish with less than the Length at first maturity (Lm) constitutes 67.3% for inexpensive species and 77.05% for expensive species. The loss of biomass in the inexpensive species was estimated at 3268 tons and the loss in income was 199 million Egyptian pounds (LE). The loss of biomass of expensive species was calculated at 1455 tons and the loss of income was 175 million LE. The total loss of biomass was 4723 tons and 374 million LE due to fishing violations and the use of illegal nets in only one fishing season. For proper management, the Length at first capture (Lc) must be increased by widening the nets mesh size. Legal fishing methods and the development of appropriate non-traditional methods for the management of Bardawil Lagoon must be applied. Ó 2019 National Institute of Oceanography and Fisheries. Hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Introduction Lake Bardawil is considered one of the most economic water masses because of its high-quality fish production, which is exported to Europe, as well as its non-polluted habitat. This lake does not suffer from the deterioration of fish quality and fish products like other Egyptian lakes (El-Halag et al., 2013). Bardawil Lagoon’s production is amounted to 2500–3000 tons of fish composed of 50% sea bream, 45% mullets and 5% miscellaneous (Fouda et al., 1985). Seven species (sea bream, sea bass, grey mullet, common sole, Egyptian sole, thin lip grey mullet and shrimp) are targeted in the lagoon while more than 20 species and two threatened ones (turtle and seahorse) are caught as bycatch (Mehanna et al., 2011). In 2014 the sea bream, sea bass, solea, shrimp and crab were represented by about 8.3%, 1.7%, 5.3%, 22.6%, and 18.8% respectively (GAFRD, 2014). About 5000 local fishermen are working in the lagoon using different kinds of fishing gears; some of them are very harmful to the
Peer review under responsibility of National Institute of Oceanography and Fisheries. ⇑ Corresponding author at: Fisheries Division, Fisheries Biology Lab., National Institute of Oceanography and Fisheries, Egypt. E-mail address: [email protected] (K.A.Sh. Shalloof).
lagoon’s fisheries. In 1990, 786 fishing boats that used the Dabba method (trammel net) were operating in the lagoon. They represented about 81.5% of the total fishing licenses that worked in Bardawil Lagoon (Ameran, 2004). Breikaa (1997) recorded two main fishing methods that are used in Bardawil Lagoon, namely Dabba and Bouss (Veranda or aerial traps) methods. Dabba fishing method contributed by 847 fishing boats during 1996; about 79% of the fishing fleet of which each fishing boat reached about 6 m in length, 1.8 m in width and with 6–25/HP outboard motor. Salem and El-Aiatt (2012) stated that the shrimp fisheries were caught by small trawlers, and increased rapidly since 1995 with the development of the shrimp biomass in the lagoon. Salem and El-Aiatt (2013) described the trammel small boats in Bardawil Lagoon; 6 m in length and powered by 9.9/HP outboard motor. On the other hand, Crespi (2002) illustrated that mullet species (Mugil spp., Liza spp.), common sole, Solea solea (L.), sea bass, D. labrax (L.) and the common cuttlefish were the major target species for the gill and trammel nets. Gianna (1994) recorded the targeted species of trammel net in the Adriatic Sea and Tyrrhenian Sea: the striped sea bream (Lithognathus mormyrus), red mullet (Mullus barbatus), blotched picarel (Spicara flexuosa), common sole (Solea solea), tub gurnard (Trigla lucerna) and common cuttlefish (Sepia officinalis).
https://doi.org/10.1016/j.ejar.2019.03.001 1687-4285/Ó 2019 National Institute of Oceanography and Fisheries. Hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
60
A.A.O. El-Aiatt et al. / Egyptian Journal of Aquatic Research 45 (2019) 59–65
Besides, crab gill nets are mostly suitable for collecting crab species, as they have less impact on the sea grass ecosystem than trawl or push nets. Collapsible crab traps are not suitable because bait does not attract berried female crabs (Xiao and Kumar, 2004). Also, Nitiratsuwan (2009) reported that crab gill nets caught more berried crabs than collapsible crab traps. Moreover, Mehanna et al. (2011) studied the effects of shrimp bottom trawling on the Bardawil Lagoon fisheries and showed that a trawler operating in Bardawil Lagoon lands about 66 kg of bycatch per two boats per day, on average. Some of the bycatch may include rabbit fish, sparid species, sardine, eel and small groupers. For this landed part of the bycatch, the price does not exceed 5 LE per kg. Also, they reported that bycatches are generally uncontrolled and may pose a risk to the assortment of the species that are facing extinction while causing deterioration to the health of the ecosystem. In addition, bottom trawling also affects the ecosystem by its physical impact on sea beds and bottom habitats. Furthermore, Mehanna (2006a, 2006b) mentioned that the serious change in catch composition during the last 20 years in Lake Bardawil can be referred to the change in the ecological conditions of the lake, uncontrolled fish exporting policy and the overexploitation since the late 80’s until now. These factors lead to the decreasing of sea bream and sea bass production. The predomination of crustacean species led to the introduction of the Kalsa fishing method (trawl nets). This fishing technique was destructive as it contributed to the catching of fish fry, especially bottom feeder like sea bream and sea bass, as well as the progressive decline and collapse of their stocks. The present work describes the negative impact of the irregularity of the used fishing methods, as well as the effect of catching small-sized fish before reaching sexual maturity in Bardawil Lake. Also, it aims to give information on the loss in biomass and income resulting from these irregularities. Material and methods Area of study The study was carried out in Bardawil Lagoon (Fig. 1); situated in the north of Sinai Peninsula. The fundamental contacts between the Mediterranean Sea and the lake are via two man-made canals; the Western Canal (Boughaz I) and the Eastern Canal (Boughaz II). There is additionally a third narrow natural boughaz referred to as El-Zaranik at the eastern edge of the lagoon. The lagoon is overly shallow and the water levels never surpass three meters in depth
(El-Halag et al., 2013). The water exchange between the lagoon and the Mediterranean Sea through the inlets plays a significant function in the water salinity standard (Abd Ellah and Hussein, 2009). It should be noted that the fish production of Bardawil Lagoon during the period from 1985 to 2015 was obtained from the statistics year book of GAFRD (General Authority for Fish Resources Development). Catch evaluation Monthly random samples were collected from three landing sites, El-Nasr, Oghzoan and El-Telol port, as shown in Fig. 1, during fishing season 2015, from April 2015 to January 2016. The following data were estimated: 1. The total number of fish samples for each species collected. 2. Length-weight relationship (was demonstrated by the potential equation (W = a Lb, Ricker, 1975), where W is the total weight (g), and L is the total length (cm). 3. The Length at first capture Lc. 4. The Length at first maturity (Lm) gathered from published papers for each species in the same area or nearby areas (Table 1). 5. The number of fish with lengths less than Lm 6. The percentage of fish with lengths less than Lm = (number of fish sample less than Lm)/(total sample) * 100. 7. The catch from fish less than Lm (Tons) = % of fish with length less than Lm total catch for all species. 8. The weight at first maturity Wm = a Lbm Where a and b are constants of length-weight relationship W = a Lb 9. The average weight for fish smaller than length at first maturity (w). 10. The natural mortality (M) can be computed by the following equation: M = (w)( 1/3), where w is the mean fish weights for fish smaller than Lm (Ursin, 1967). 11. The equation that describes the loss of biomass as a result of fishing small fish, is as follows: QA = [(1000/w) * Wm]/(1000) (1 M) (Najmudeen and Sathiadhas, 2008) where: QA = Adult fish magnitude congruent to 1 kg of small fish after a cycle of (t) years. Wm = weight of the fish at the Length at first maturity after a period of (t) years. w = Average weight for fish smaller than the Length at first maturity. 12. Losses of biomass = output of the previous equation the product from the small fish of each species.
Fig. 1. Bardawil Lagoon; area of study showing Landing sites.
A.A.O. El-Aiatt et al. / Egyptian Journal of Aquatic Research 45 (2019) 59–65 Table 1 Length at first maturity (Lm) and average annual prices. Fish species
Lm (cm)
Reference
Price (LE 1000/ton)
Mugil cephalus Sparus aurata Portunus pelagicus Siganus rivulatus Terapon puta Penaeus semisulcatus Epinephelus aeneus Solea vulgaris Liza ramada Liza aurata Hemiramphus far Dicentrarchus labrax
31.1 24.5 10.2 14.4 13.2 5.8 47.1 19.1 28.7 23.1 23.1 31.0
El-Aiatt (2013) Mehanna (2007) Emam, (2010) Kabil (2015) kassem (2017) Ameran (2004) Rafail et al. (1969) Shokry (2013) Mehanna (2006a, 2006b) Mehanna (2006a, 2006b) Mahmoud (in press) Salem (2004)
50 150 80 40 25 100 250 120 40 40 40 100
13. Losses of income = Losses of biomass average price. Results and discussion The Bardawil Lagoon has experienced many problems, which might lead to environmental breakdown, insufficiency of fish catch and radical changes in its ecosystem. The drying up of some regions within the lagoon and subsequently loss of its biological and economic magnitude is due to the repeated changes of inward shape and dimension of the lake (Abd Ellah and Hussein, 2009). As shown in Fig. 2, the development of the total catch production peaked during 2009 and was the lowest in 1992. This may have been affected by the number of fishing boats, the number of fishermen and environmental conditions. The closure of the boughaz, connecting the lagoon with the Mediterranean during sea rises, imposes the danger of drying up the lagoon and the subsequent loss of its biological and economic value. Moreover, an extensive salt production system; constructed in the eastern part of the lagoon; leads also to considerable ecological changes. Furthermore, there is an increasing pressure to establish touristic developments along the lake’s shores (Mageed, 2006). From Table 2 and Fig. 2, species composition of the catch of Bardawil Lagoon, during the period from 1985 to 2015, was Portunus pelagicus, Penaeus semisulcatus, Mugil cephalus, Sparus aurata, Liza ramada, Liza aurata, Solea solea, Dicentrarchus labrax, Signus rivulatus, Terapon puta, Hemiramphus far, Epinephelus aeneus and others. Ben-Tuvia (1975) listed about 60 species of fishes gathered from the lagoon during the 1970s, but Khalil et al. (2002) listed up to 44 species only from Bardawil Lagoon. On the other hand, Mehanna (2006a, 2006b) reported that the total annual commercial landings of Bardawil Lagoon varied between 2226 and 5410 tons (1998–2011) earning almost 96 million LE. She also mentioned that the catch of Bardawil Lagoon is composed mostly of M. cephalus, L. ramada and L. aurata (family: Mugilidae); S. aurata (Sparidae) D. labrax and D. punctatus (Moronidae); Solea spp. (Soleidae); A. regius (Sciaenidae); Epinephelus spp. (Serranidae), and Siganus spp. (Siganidae) as well as crustacean species that
61
are represented in the catch by shrimps; mainly Metapenaeus stebbingi; and crabs; mainly P. pelagicus. The author also pointed out that the common commercial fishes of Bardawil Lagoon are the gilthead sea bream (S. aurata), grey mullets (Mugilidae), the sea bass (D. labrax) and the common sole (Solea solea). In the present study, the average total catch of Bardawil Lagoon during the period from 1985 to 2015 was 2970 tons. In India, Kumar et al. (2013) recorded that about 76% of the bycatch weight was gathered from crab gill net. This was supported by Fazrul et al. (2015) who reported that 50.8% of the bycatch was also entangled by crab gill net. The three most principal bycatch species were horseshoe crab (Carcinoscorpius rotundicauda), mud crab (Scylla serrata) and spotted catfish (Arius maculates). Although crab gill net was designed as selective fishing gear, it still captures many non-target species or bycatch. So, in order to manage marine fisheries effectively, the problem of bycatch must be assessed and managed (Alverson et al., 1994). The average catch from the crabs was 662 tons in the period from 1985 to 2015; representing 22.3% of the total yield. Shrimp was the second important catch in the yield; representing 18.2% of the total yield. It was followed by mullet with an average catch of 441 tons in the period from 1985 to 2015, which amounted to 14.8% of the total yield, followed by sea bream with an average catch of 434 tons, which amounted to 14.6% of the total yield. Liza ramada ranked in the 5th rank of catch production, since its average catch was 294 tons and amounted to 9.9% of the total yield. Liza aurta, Solea solea, Dicentrarchus labrax, Terapon puta and Siganus rivulatus were represented by 7.2, 4.9, 2.2, 1.5 and 1.4% of the total yield respectively. Hemiramphus far and Epinephelus aeneus represented 0.7% and 0.5%, respectively of the total yield production (Table 2). Table 3 and Fig. 3 summarize the catch composition during fishing season 2015 in Bardawil Lagoon. Also, the result shows that more than 12 species weighing 4704 tons were caught by different fishing methods. Sadek and Ameran (1984) reported that the catch of Bardawil Lagoon was composed mainly of the gilthead sea bream, with an average yield of about 48.49% of the total catch. The collapse in the production of sea bream in fishing season 2015 may be attributed to the difference in the ecological conditions and also the use of illegal fishing gears. Abd Ellah and Hussein (2009) concluded that the majority of the lagoon is frequently hyper saline. Ben-Tuvia (1979) mentioned that the abnormally high salinities prevent both the adult and the young fish from settling in the lagoon. In the present study, the catch composition of Bardawil Lagoon was mainly dominated by crustaceans (crabs and shrimps). These results agree with other studies obtained by Mehanna (2006a, 2006b). She mentioned that crustaceans’ (shrimps and crabs) production has been extremely elevated in the lagoon, going up to 60% of the total catch in 2005, affecting the catch of extra commercial fish species like sea bream and sea bass. Also she mentioned that the appearance of crustacean species led to the introduction of a new fishing technique called the Kalsa fishing technique or
Fig. 2. Annual catch of Bardawil Lagoon (1985–2015).
62
A.A.O. El-Aiatt et al. / Egyptian Journal of Aquatic Research 45 (2019) 59–65
Table 2 The Annual variation in the total fish yield and species composition of the Bardawil Lagoon from 1985 to 2015 (GAFRD, 2016). Years
S. aurata
D. labrax
S. solea
E. aeneus
A. regius
M. cephalus
L. ramada
L. aurata
P. semisulcatus
P. pelagicus
T. puta
H. far
S. rivulatus
A. anguilla
Others
Total
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 average %
1418 1303 1027 1022 952 977 956 280 274 76 110 146 176 228 139 253 223 266 279 339 293 274 303 336 315 304 214 256 240 230 239 434 14.6
135 84 83 94 157 186 157 58 40 59 10 26 71 43 43 31 57 25 40 27 35 44 69 90 81 46 28 45 40 47 56 65 2.2
130 42 70 101 94 136 133 62 118 57 79 149 139 134 165 149 142 140 159 127 168 292 281 343 232 123 194 159 122 147 170 147 4.9
11 42 17 8 12 20 22 9 3 6 4 11 11 14 9 10 11 9 6 9 13 22 13 28 28 25 2 7 10 19 21 14 0.5
2 11 5 2 2 2 1 1 1 1 1 2 1 0 0 3 0 3 3 3 3 5 3 4 4 5 4 6 7 7 9 3 0.1
153 199 122 163 211 284 141 151 163 213 361 466 422 422 510 524 578 651 600 366 405 480 576 851 748 606 739 659 379 555 962 441 14.8
126 182 329 193 170 214 168 180 373 206 339 393 272 337 320 347 330 350 318 258 269 268 301 347 308 444 374 353 281 298 469 294 9.9
72 101 158 395 459 910 882 559 697 660 104 58 85 90 76 82 81 81 82 79 79 76 74 100 76 83 78 74 74 74 161 215 7.2
0 0 0 0 0 0 0 0 0 2 274 76 288 271 576 787 595 814 808 329 775 1264 1569 1428 1355 1221 1176 1099 1149 624 302 541 18.2
0 0 20 25 31 26 13 70 89 206 492 99 507 552 658 754 520 609 953 570 1322 1184 1343 1611 2053 1457 1201 929 734 519 1973 662 22.3
0 0 0 0 0 0 0 0 0 0 0 0 0 71 76 62 51 50 32 71 102 83 80 89 33 52 84 108 87 147 65 43 1.5
0 0 0 0 0 0 0 0 0 0 0 0 0 37 45 12 18 14 6 9 12 29 19 24 72 103 87 43 32 23 49 20 0.7
0 0 0 0 0 0 0 0 0 0 0 0 0 60 108 55 169 46 5 9 19 49 19 69 61 212 305 51 8 19 49 42 1.4
0 0 0 0 0 0 0 0 0 0 0 0 0 3 5 47 10 10 14 12 15 35 26 35 30 26 12 16 18 15 21 11 0.4
4 6 48 19 12 6 0 0 52 14 59 109 157 15 28 28 17 14 20 18 24 37 51 38 16 27 29 40 56 35 158 37 1.2
2051 1972 1878 2023 2100 2762 2473 1371 1810 1500 1832 1536 2128 2277 2758 3145 2801 3082 3326 2227 3534 4142 4729 5393 5410 4733 4529 3845 3237 2758 4704 2970 100.0
Table 3 Total catches and species composition from Bardawil Lagoon during season 2015. Fish species
Catch (Tons)
% of total catch
Total Number of the sample
Number of the sample of small fish
% of small fish
Total catch of small fish (Tons)
Sparus aurata Dicentrarchus labrax Penaeus semisulcatus Epinephelus aeneus Solea solea Portunus pelagicus Mugil cephalus Liza ramada Liza aurata Siganus rivulatus Terapon puta Hemiramphus far Others Total
239 56 302 30 170 1973 962 469 161 49 65 49 179 4704
5.08 1.19 6.42 0.64 3.61 41.94 20.45 9.97 3.42 1.04 1.38 1.04 3.81
1630 1269 939 509 2142 2147 1931 1567 160 2722 3424 976
1350 918 921 505 1313 1348 1291 1382 157 1794 2205 528
83 72 98 99 61 63 67 88 98 66 64 54
198 41 296 30 104 1239 643 414 158 32 42 27
19,416
13,712
70.6
trawl nets. This fishing method was very destructive, and contributed to catching fish fry of bottom feeders, like soles, sea bream and sea bass, resulting in the progressive decline of their stocks. The Length at first capture (Lc) of different species in Bardawil Lagoon was less than the length at first maturity (Lm). The Lm of M. cephalus, S. aurata and D. labrax was 31.1, 24.5 and 31.0 cm, meanwhile, Lc = 29.0, 18.5 and 27.8 cm for the previous species respectively (Tables 1 and 4). Table 3 summarizes the catch composition of small fish (less than the Length at first maturity). Also this table represents the negative impact of the presence of small fish of the inexpensive species (P. pelagicus, M. cephalus, L. ramada, L. aurata, S. rivulatus,
T. puta and H. far) in the catch of boats, as a result of using illegal fishing nets. Generally the percentage of small fish from inexpensive and expensive fish amounted to 70.6% (total sample was 19,416 and total sample from small fish was 13,712) (Table 3). While, the percentage of small fish of inexpensive species with length less than the Length at first maturity (Lm) was 67.3%, (total sample 12,927 and total small fish sample 8705). One of the basic regulations for the sustainability of the fish community is to allow the fish to spawn at least once before fishing. Hence, the minimum legal size of fish must be greater than the Length at first maturity (Öztekin, 2007). As shown in Table 3 the samples that were collected from the production of expensive species include Sparus aurata, Dicentrarchus
63
A.A.O. El-Aiatt et al. / Egyptian Journal of Aquatic Research 45 (2019) 59–65
Fig. 3. Species composition during fishing season 2015 in Bardawil Lagoon.
Table 4 Different biological parameters for local species in Bardawil Lagoon during 2015. Items
P. pelagicus
M. cephalus
L. Ramada
L. aurata
S. rivulatus
T. puta
H. far
S. aurata
D. labrax
P. semisulcatus
E. aeneus
S. solea
Length at the first capture Lc Average weight of fish under Lm50 (w) Constant formula of L-W relationship (a) Constant formula of L-W relationship (b)
9.5 45.4
29 217.0
23.7 103.1
17 40.9
13.5 18.3
12.6 17.2
22.6 58.5
18.5 91.9
27.8 184.2
2.4 5.2
34 470.7
17.7 50.0
0.0479
0.0097
0.0072
0.0114
0.0072
0.0106
0.0042
0.0186
0.0165
0.1605
0.0191
0.0136
3.1825
3.0219
3.0378
2.8805
3.0907
3.0004
3.1046
2.909
2.8444
2.9601
2.8695
2.9206
Fig. 4. Total biomass loss (ton) from inexpensive species caught by different fishing gears during 2015.
Fig. 5. Total income loss (million LE) of inexpensive species caught by different fishing gears during 2015.
labrax, Penaeus semisulcatus, Epinephelus aeneus and Solea solea. The classification depends on the Length at first maturity (Lm); 1 – small fish less than Lm, 2 – mature fish from Lm and greater than Lm. The proportion of small fish represents 77.05% of the production (total sample 6498 and total small fish sample 5007). This means that, the percentage of small fish with a length less than the Length at first
maturity (Lm) constitutes 67.3% for inexpensive species and 77.05% for expensive species. This may be due to using illegal fishing methods in the lagoon. The presence of small fishes more than 50% indicates an overfishing process in the lagoon. It is worth mentioning that there are two main fishing methods that are certified to operate in Bardawil Lagoon; namely Dabba and
64
A.A.O. El-Aiatt et al. / Egyptian Journal of Aquatic Research 45 (2019) 59–65
Fig. 6. Total biomass loss (ton) of expensive species caught by different fishing gears during 2015.
Fig. 7. Total income loss (million LE) of expensive species caught by different fishing gears during 2015.
Bouss methods. Other illegal fishing gears that operate in the lagoon are namely Dahbana, Kalsa (trawl net), Sinnar (long line), Cioncholla (looks like Dahbana); beside the crabs’ gear ‘‘Isfinkes gear” (Mehanna, 2006a, 2006b). In order to protect fish stock and to enable them to participate at least once in reproduction, several measures should be taken into consideration such as an urgent increase in the mesh size of the already used nets as well as the evaluation of all fishing methods in the lagoon and prohibiting the dangerous ones. The bycatches influence on the ecosystem as they increase the mortality of the incidentally captured species and have a negative economic impact when they consist of the juveniles of the commercially important species as well as other fish used as live food; hence, they are considered as a hazard to food security and viable fisheries (FAO, 2014). Jomaa (2018) found a negative impact of the purse – seine, trammel net and trawl net on the Mediterranean catch off the Sinai coast. He found that the percentage of small fish was 55% of the catch of the purse–seine, 27.5% of the catch of the trammel net and 42.2% of the trawl net. The negative impact on the biomass was 923.2, 1061.7 and 160.8 tons for each of the purse–seine, trammel net and trawl net respectively, with a total of 2145.4 tons in one fishing season of 2016 amounting to 212 million Egyptian pounds. In the present study, the loss in biomass of inexpensive species was estimated as 3268 tons and the loss in income was 199 million LE. The loss in biomass of expensive species was calculated as 1455 tons and the loss of income was 175 million LE. The total loss in biomass was 4723 tons and 374 million LE due to unlawful fishing methods and the use of illegal nets in one fishing season. Salem et al (2018) found that the landing of small fish has led to more losses of stock biomass, which formed about 345 tons and about
23.6 million LE losses in income in one fishing season, 2016 in Bardawil Lagoon. The current results indicated that the landing of small fish from inexpensive species leads to more losses of stock biomass, which formed 1525, 777.3, 609.8, 265.1, 29.9, 36.4 and 24.2 tons for Portunus pelagicus, Mugil cephalus, Liza ramada, Liza aurata, Siganus rivulatus, Terapon puta and Hemiramphus far respectively (total loss biomass = 3268 ton), and 199 million LE losses in income in one fishing season, 2015; 122.0, 38.9, 24.4, 10.6, 1.2, 0.9 and 1.0 million LE for P. pelagicus, M. cephalus, L. ramada, L. aurata, S. rivulatus, T. puta and H. far respectively (Figs. 4 and 5). It has been found that the landing of small fish from expensive species leads to more losses of stock biomass, which formed 343, 52, 705, 67 and 114 tons for S. aurata, D. labrax, P. semisulcatus, groupers E. aeneus and sole S. solea, respectively (total loss biomass = 1455 ton), and 175 million LE losses in income in one fishing season, 2015; 51.4, 5.2, 71, 16.6 and 13.6 million LE for S. aurata, D. labrax, P. semisulcatus, E. aeneus and S. solea respectively, as shown in Figs. 6 and 7. Gaber (2012) reported that the losses in biomass in crabs, P. pelagicus 371 tons; shrimp 353 tons; groupers, E. aeneus 398 tons; Rabbit fish, Solea spp 148.2 tons; and Snapper, T. puta 82.8 tons in the Mediterranean coast of Sinai, during 2010. Jomaa (2018) reported the losses in biomass in groupers E. aeneus = 181 tons; crabs P. pelagicus = 512 tons; shrimp P. semisulcatus = 25 tons; mullet M. cephalus = 64.6 tons; sea bream S. aurata = 6.6 tons; rabbit fish = S. rivulatus 61.8 tons; and snapper = T. puta 10.3 tons in the Mediterranean coast of Sinai, during 2016. Also Salem et al (2018) recorded the losses in biomass of several species such as thin lip grey-mullet L. ramada = 132.8 tons; grey-mullet M. cephalus = 116.6 tons; sea bream S. aurata = 68.3 tons; sole (S. solea) = 7.4 tons; sea bass D. labrax = 7.4 tons; and crabs P. pelagicus = 13.1 tons from using gill net in Bardawil Lagoon during 2016.
A.A.O. El-Aiatt et al. / Egyptian Journal of Aquatic Research 45 (2019) 59–65
Conclusion This study gives a comprehensive descriptive survey of the production in Lake Bardawil from 1985 to 2015. The development of the total catch production peaked during 2009 and was the lowest in 1992. The percentage of small fish with a length less than the Length at first maturity (Lm) constitutes more than 50% for inexpensive and expensive species indicating an overfishing process in the lagoon. The total loss in biomass was 4723 tons and 374 million LE due to unlawful fishing methods. For better-informed management decisions, the Length at first capture (Lc) must be increased by enlarging the size of the mesh of the fishing nets. We also recommend the prohibition of the destructive gears like ‘‘Kalsa” and other illegal nets. More investigations are needed based on the biology of the economic fishes in Bardawil Lagoon and gear selectivity of different nets to manage and protect this vital resource.
References Abd Ellah, Radwan G., Hussein, Maged M., 2009. Physical limnology of Bardawil Lagoon, Egypt. American-Eurasian J. Agric. Environ. Sci. 5 (3), 331–336. Alverson, D.L., Freeberg, M.H., Murawski, S.A., Pope, J.G., 1994. A Global Assessment of Fisheries Bycatch and Discards, FAO Fish. Tech. Paper 339. FAO, Rome, p. 233. Ameran, M.A.A., 2004. Studies on the Crustacean Fishery in Bardawil Lagoon (Ph.D. Thesis). Faculty of Environmental Agricultural Science, Suez Canal Univ, AlArish. Ben-Tuvia, A., 1975. Comparison of the fish fauna in the Bardawil Lagoon and the Bitter Lakes. Rapp. Commun. Int. Mer Médit. 23 (3), 125–126. Ben-Tuvia, A., Golani, D., 1979. Ten years of fisheries biology investigations of the Bardawil Lagoon. Fish. Fish Breed. Israel 14 (2), 29–37 (in Hebrew with English abstr). Breikaa, M.I.M., 1997. Fisheries management on the Bardwell Lagoon, Northern Sinai, Egypt. J. Aquat. Biol. Fish 1 (2), 291–307. Crespi, V.M., 2002. Recent evolution of the fishing exploitation in the Thau lagoon, France. Fish. Manage. Ecol. 9 (19), 29. El-Aiatt, A.A.O., 2013. Biological Studies on Family Mugiliadae in Bardawil Lagoon (M.SC. Thesis). Fac. Agriculture, Suez Canal University. El-Halag, Rabie S.F., Shaker, Ibrahim M., Mehanna, Sahar F., Othman, Mohammed F., Farouk, Alam El-Deen, 2013. Impact of some environmental condition on water quality and some heavy metals in water from Bardawil Lake. New York Sci. J. 6 (11), 5–13. Emam, W.W.M., 2010. Ecological and Population Dynamic Studies on Some Crab Species in Bardawil Lagoon, Egypt (MSc Thesis). Zoology Department, Faculty of Science, Ain Shams University. FAO, 2014. In: The State of World Fisheries and Aquaculture 2014. FAO fisheries Technical Paper, Rome, p. 223. Fazrul, H., Hajisamae, S., Ikhwanuddin, M., Pradit, S., 2015. Assessing Impact of Crab gill net Fishery to Bycatch Population in the Lower Gulf of Thailand. Turk. J. Fish. Aquat. Sci. 15, 761–771. Fouda, M.F., Wanas, M.K., Saleh, M.A., 1985. Ecology of Bardwell Lagoon, A Report to the Oil Pollution Research Unit, Pembroke. UK for BP Petroleum LTD, Egypt. Gaber, M., 2012. Studies on Fish Production of Mediterranean Coast in North Sinai Governorate (Ph.D. Thesis). Faculty of Agricultural at Cairo, EL-Azhar University. GAFRD, 2014. Report of General Authority for Fish Resources Development on Egyptian Fishery. GAFRD, 2016. Annual Fishery Statistics Report, General Authority for Fish Resources Development (GAFRD). Ministry of Agriculture, Cairo, Egypt. Gianna, F., 1994. Trammel and Gill-nets Selectivity in the Adriatic Sea and Tyrrhenian Sea. Participating Institutions: Consiglio Nazionale delle Richerche (CNR), Istituto di Ricerche Sulla Pesca Marittima (IRPEM), 60125 Ancona, Italy.
65
Jomaa, S.M.S., 2018. Studies on Traditional Characters of the Fishing of Eastern Mediterranean (North Sinai Coast) (M.Sc. Thesis). Fac. Agriculture, Arish University. Kabil, S.M.A., 2015. Studies on Biological and Dynamics of Siganidae Family in the Bardawil Lagoon (M.Sc. in Environmental Agricultural Sciences). Suez Canal University. Kassem, S., 2017. Biological and Dynamical Studies on the Small Scaled terapon Stock (Family: Terapontidae) in Bardawil Lagoon (M.Sc. Thesis). Faculty of Environmental Agricultural Sciences, Arish University, Egypt. Khalil, M.T., El-Ganainy, A.A., Yassien, M.M., 2002. Ecological Survey of Bardawil Nature Protectorate; Fishes and Fisheries, MedWetCoast project. EEAA, Egypt. Kumar, A., Sundaramoorthy, B., Jakhar, J.K., 2013. Standardization of crab bottom set Gillnet for reduction of Bycatch at Thoothukudi coast, Tamilnadu, India. Arch. Appl. Sci. Res. 5, 74–81. Mahmoud, H.S., in press. Biological and Dynamical Studies on the Garfish (Family: Belonidae) in Bardawil Lagoon (MSc Thesis). Fac. Env. Agric. Sci. Arish Univ. ELArish, North Sinai. Mageed, A.A., 2006. Spatio-temporal variations of zooplankton community in the hypersaline lagoon of Bardawil, North Sinai – Egypt. Egypt J. Aquat. Res. 32 (1), 168–183. Mehanna, S., 2006a. Fishes and fisheries. In: Khalil, M., Shaltout, K. (Eds.), Lake Bardawil and Zaranik Protected Area. Publication of National biodiversity unit, 15 (Chapter 9). Mehanna, S., 2006b. Lake Bardawil fisheries: current status and future sight. J. Egypt Ger. Soc. Zool. 51 (D), 91–105. Mehanna, S.F., 2007. Stock assessment and management of the Egyptian sole Solea aegyptiaca Chabanaud, 1927 (Osteichthyes: Soleidae), in the Southeastern Mediterranean, Egypt. Turk. J. Zool. 31, 379–388. Mehanna, S., El-Aiatt, A., Salem, M., 2011. An investigation of the impacts of shrimp bottom trawling on the Bardawil Lagoon fisheries, Egypt (Egyptian J. of Aquatic Biology and Fisheries. 15, (3). ISSN 1110 – 6131). In: 4th International conference on Fisheries and Aquaculture, 3-5 October, Cairo, Egypt, pp. 407– 416. Najmudeen, T.M., Sathiadhas, R., 2008. Economic impact of juvenile fishing in a tropical multi-gear fishery. Fish Res. 92 (2), 322–332. Nitiratsuwan, T., 2009. ‘‘Sustainable fisheries management for the blue swimming crab (Portunus pelagicus Linnaeus, 1758) in Trang province”. Area Based Dev. Res. J. 1, 28–42. Öztekin, A., 2007. Sarpa (Sarpa salpa L.1758) balıg˘ı avcılıg˘ında kullanılan sade alamana ag˘larının seçicilig˘i. Çanakkale onsekiz mart Üniversitesi Fen Bilimleri Enstitüsü, Yüksek Lisans Tezi, 28s, Çanakkale. Rafail, S.Z., Daoud, W.L., Hilal, M.M., 1969. Long line Mediterranean fisheries studies west of Alexandria. Stud. Rev. Gen. Fish. Counc. Mediterr. 42, 3–16. Ricker, W.E., 1975. Computation and interpretation of biological statistics of fish populations. J. Fish. Res. Board Can. 191, 1–367. Sadek, S., Ameran, M.A.A., 1984. Bardawil LAGOON Fish Development Resources for the Period 1979/83. GAFRD, Cairo, Egypt, p. 170. Salem, A.A., Reyad, I.R., El Aiatt, A.A.O., Gaber, M., Rahnda, E.M., Rana, E.M., 2018. Biological and economical evaluation of bycatch and discards of fisheries for gill net in Bardawil Lagoon. J. Egypt. Acad. Soc. Environ. Dev. 19 (1), 107–116. Salem, M., 2004. Biological Studies for the Fishery Regulation and management of the Bardawil Lagoon (Ph.D. Thesis). Fac. Env. Agric. Sci. Suez Canal Univ, ElArish, North Sinai, Egypt. Salem, M., El-Aiatt, A., 2013. Improvement of trammel net landing and reduction of fishing for gilthead sea bream, Sparus aurata juveniles in Bardawil Lagoon, North Sinai, Egypt. J. Anim. Poultry Fish Prod. Suez Canal Univ. 1. Salem, M., El-Aiatt, A., 2012. Population dynamics and fisheries management of Penaeus semisulcatus exploited by shrimp trawl of Bardawil Lagoon, North Sinai, Egypt. Egypt. J. Anim. Prod. 49 (Suppl. Issue), 185–191. Shokry, S.M., 2013. Fisheries Characteristics and Population dynamics of Commercial Species of Family Soleidae in Bardawil Lagoon, North Sinai, Egypt (M.Sc. Fac. Sci.). Suez Canal Univ.. Ursin, E., 1967. A mathematical model of some aspects of fish growth, respiration and mortality. J. Fish. Res. Board Can. 24, 2355–2453. Xiao, Y.S., Kumar, M., 2004. Sex ratio, and probability of sexual maturity of females at size of the blue swimmer crab, Portunus pelagicus (Linneaus), off Southern Australia. Fish. Res. 68, 271–282.