Controlling rate of egg development in vendace (Coregonus albula L.) to increase larval growth rate in stocked lakes

Aquaculture, 51 (1986) 195-205 Elsevier Science Publishers B.V.,

195 Amsterdam

-

Printed

in The Netherlands

CONTROLLING RATE OF EGG DEVELOPMENT IN VENDACE (COREGONUS ALBULA L.) TO INCREASE LARVAL GROWTH RATE IN STOCKED LAKES

M. LUCZYNSKI’,

W. DEMBINSKI’

and L. CHYBOWSKI’

‘Institute of Ichthyobiology and Fisheries, Academy of Agriculture IO-957 Olsztyn-Kortowo, Bl. 37 (Poland) aInland Fisheries Institute, 1 O-957 Olsztyn-Kortowo, Bl. 5 (Poland) (Accepted

24 September

and

Technology,

1985)

ABSTRACT Luczynski, M., Dembinski, W. and Chybowski, L., 1986. Controlling rate of egg develqpment in vendace (Coregonus albula L.) to increase larval growth rate in stocked lakes. Aquaculture, 51: 195-205. Successive batches of vendace (Coregonus albula) larvae, obtained by a hatching delay technique, were stocked in lake cages on 17 and 23 April and on 1, 9, and 18 May, 1979. The lake water temperature increased from about 6°C in mid-April to about 12-14°C in mid-May, 1979. Available nauplii and copepodites, the most suitable food organisms for vendace larvae, increased within the same period from 20-30 to 100-300 individuals 1-l. Higher water temperature and more abundant food supply resulted in faster growth of larvae stocked at later dates. Accordingly, fish raised from the successive batches of larvae attained a total length of 20 mm after 31, 28, 22, 19, and 21 days of rearing, respectively. Increased chances of survival in the stocked lakes are discussed in light of these higher larval growth rates.

INTRODUCTION

Coregoninae embryos incubated in commercial hatcheries hatch in spring, when water temperatures rise after the ice cover recedes from lakes (Luczynski, 1985). At this time, larvae stocked in lakes face a period of low water temperature and limited food supply; in some cases larvae from hatcheries supplied with higher temperature well water may be liberated when the ice cover is still present (Budych, 1971). Owing to the poor environmental conditions at liberation there is a danger of starvation (Dabrowski, 1975) or at least of very slow growth of larvae and consequent lengthening of the period of high vulnerability to predation (Lindstriim, 1962) and diminished chance of survival (Einsele, 1963). Low larval survival is believed to be the main cause of the commonly observed failure of Coregoninae stocking programs (Christie, 1963; Bernatowicz et al., 1975).

0044-8486/86/$03.50

o 1986

Elsevier

Science

Publishers

B.V.

196

Artificial incubation of Coregoninae eggs at low temperature (l--2°C) delays hatching until both the natural water temperature and the density of zooplankton in lakes have become conducive to faster growth of stocked larvae (Niimann, 1953; Luczynski, 1984a). Such a technique could improve the results of stocking lakes with Coregoninae larvae (Niimann, 1967, 1970). Under Polish climatic conditions the first 10 days of May appear suitable, in terms of water temperature and zooplankton density, for stocking lakes (Patalas, 1963; Gliwicz, 1977; Szczerbowski and Mamcarz, 1984). In this study we checked these assumptions by incubating vendace eggs (C. albula) in different temperature regimes to obtain different hatching times (Luczynski, 198413). The larvae were reared in lake cages to observe their viability and growth rates in relation to changing environmental conditions in the lake. MATERIALS

AND METHODS

Eggs Ripe spawners of C. albula were gillnetted in Lake Kobylocha on 21 November 1978, and in Lake Kosno on 30 November 1978. Spawners were stripped and the freshly fertilized and water-hardened eggs were transported to the commercial Coregoninae hatchery in Janowo. Egg incubation

in the hatchery

In the hatchery both batches of eggs were incubated in cylinders held in separate 7-1 glass jars. The bottom and top covers of the cylinders were made of plastic screening, and the cylinders were suspended vertically in the jars. The eggs were examined twice a week, and dead eggs and hatched larvae were removed and counted. The temperature of the hatchery water supply was measured (to f O.l”C) twice daily, and daily means were calculated. Egg incubation

in the laboratory

In spring, when the water temperature in Janowo hatchery exceeded 1°C (22 March 1979), about 1 1 of eggs from both egg batches was transported in vacuum bottles from the hatchery to the laboratory (Inland Fisheries Institute, Olsztyn) and allowed to develop further in separate 7-l glass jars. Water supplied to the jars was thermoregulated (1.1 + O.O9”C), re-circulated and sterilized by UV radiation. Water temperature was measured three times daily (* O.l”C) and daily means were calculated as before. Samples of the eggs were placed in incubation cylinders as before; these were examined daily, and dead eggs and hatching larvae were removed and counted.

197

Ha tehing procedure While the eggs incubated at 1.1% were hatching, samples of eggs were taken from the same jars every few days over the protracted hatching period. These were acclimated at a rate of 1.5”C h- ’ to the temperature of the lake water supplying the laboratory (Table 1). The samples then were placed in incubation cylinders supplied with lake water. Hatching embryos and dead eggs were removed daily.

Stocking

of larvae

Five thousand viable larvae were taken from both batches of eggs during the period of mass hatching in the hatchery. The larvae were transported to Lake Wulpinskie (Olsztyn District) and placed in separate rearing cages. Similarly, 5000 larvae hatching later under the different temperature regimes were transported from the laboratory and stocked in separate cages.

Rearing in cages Each batch (5000) of vendace larvae was placed in cages (2.8 X 2.4 X 2.0 m) covered with nylon netting of 0.86 X 1.06 mm mesh size. When the fry had grown sufficiently (about 20 mm total length, TL) to be constrained by a larger mesh size, they were transferred to larger cages (2.8 X 2.4 X 3.5 m) covered with nylon netting of 1.34 X 1.50 mm mesh size. Details of the cage construction are given elsewhere (Dembinski and Falkowski, 1983). The cages were tethered on 30-m ropes. Wind action shifted the cages over an area of the lake, providing supplementation of zooplankton inside the cages; no artificial light was used to attract zooplankton. At the end of May and in early June the water temperature exceeded 20°C and became too high for vendace larvae. Moreover, later in the experiment it was impossible to clean the cages properly and frequently enough to prevent their silting and becoming overgrown with algae; hence, as the fish grew larger they occasionally faced periods of unsatisfactory food supply. In one cage, shortly after stocking with larvae, 208 specimens died; they contained air bubbles in the digestive tract. It was clear that those fish had ingested air bubbles produced by algae growing on the cage netting. It is possible that some mortality may have occurred in other cages from ingestion of air bubbles at that time. An invasion of the ectoparasite Argulus foliaceus occurred with the rising temperature. These affected the experiment from about the third week of May, synchronously with a period of very hot and windless weather. When the larvae had slightly exceeded 20 mm TL, they were transferred into deeper cages covered with larger mesh netting. We assumed that this procedure would improve environmental conditions for larval rearing. However, due to the difficulties mentioned, our assumption was not realized.

198

Therefore we decided to compare growth rates in the particular batches of larval fish from the initial period of observation until the larvae had reached 20 mm TL. Sampling Samples of n = 30 fish were taken weekly and preserved in 4% formaldehyde. The specimens obtained were measured under a microscope to the nearest 0.01 mm, dried on filter paper, and weighed to the nearest 0.1 mg. To examine the food availability for the reared larvae, samples of zooplankton from 20 1 of water were taken twice a week both from inside and outside the cages. Zooplankton samples were also taken from the surface, from 1.5 m depth and, where possible, from 3.0 m. Water temperatures were taken twice a week at the same depths as the zooplankton samples. The exterior of the cages was cleaned at least once a week to prevent accumulation of silt and algae. At the end of the rearing period all fishes from each cage were counted, and samples (n = 100) were preserved, measured and weighed. RESULTS

Hatching success Hatchability of vendace eggs varied in relation to the incubation conditions applied (Table 1). Hatching delay caused some increase in egg mortality. Additionally, when hatching was delayed excessively (trial A3, Table 1) the lake water temperature became too high (13.5-16.O”C) for vendace embryos and the acclimation temperature resulted in low hatchability of eggs (42%). TABLE 1 Thermal conditions of incubation, survival of eggs, and size of eleutberoembryos of C. albula from Lake Kosno (A) and Lake Kobylocha (B) incubated in a normal hatchery and in artificially cooled water (incubation season 1978-1979) Date of 50% hatch Source

Norma)

Delayed

Al A2 A3

23 April -

-

Bl B2

12 April -

-

9 May 18 May

1 May

Temperature Percentage of normal during hatching (“C) hatch

Mean size of eleutheroembryos Total length (mm)

Wet weight (g)

5.07.3 10.0-11.0 13.5-16.0

76 71 42

9.63 9.31 9.82

0.0032 0.0032 no data

54 41

9.02 9.09

0.0025 0.0027

3.59.0-

7.3 9.5

199

There was no clear relation between the extent length and weight of emerging eleutheroembryos, ing from vendace eggs taken from Lake Kobylocha those from Lake Kosno (Table 1). Environmental

conditions

of hatching delay and the although embryos hatchwere clearly smaller than

in Lake Wulpinskie

In 1979 the ice cover disappeared from Lake Wulpinskie about 10 April. At that time the lake water temperature started to rise (Fig. 1). The increase in temperature was pronounced during May as was the increase in zooplankton abundance. Nauplii and copepodites, the most suitable food organisms for vendace larvae, increased from about 20-30 individuals 1-l in mid-April to about 100-300 individuals 1-j in mid-May (Fig. 1). 24

22

_---

20

0.0 m

-

1.5 ml

18 6,

3.0 m

16 2

2400

14

;i; ;

12

t 0

10

i

. i 5 .e_ y 2200

i

f 3

E

600

6

.E 6

E D ‘0

600

4

.u s I 5

400

a i E 0’

200

:

0

April

Fig. 1. Water temperature in spring, 1979.

June, 1979

and the amount

of zooplankton

organisms

in Lake Wulpinskie

200 Cage rearing

Fig. 2 shows the growth of vendace larvae hatched at different times, together with lake water temperature and abundance of nauplii and copepodites. Independent of the source of stocking material (Lake Kosno or Lake Kobylocha) or of the incubation procedure (cages 1 and 3 - incubation in commercial hatchery; cages 2, 4, and 5 - laboratory-delayed hatching), larvae grew faster when hatching (and stocking) occurred later (Fig. 2). Introducing successive batches of larvae into the lake at higher water temper-

22

20

April

May

E v) i

June.1979

Fig. 2. Growth of vendace (C. aIbuZa) larvae hatched at different times Cages 1 and 2 contained larvae of vendace from Lake Kobylocha, and cages 3,4, and 5 contained larvae from Lake Kosno. The water temperature and the amounts of zooplankton organisms are shown at the bottom of the figure.

201

atures and more abundant food supply resulted in larvae from cages 1, 3, 2, 4 and 5 achieving 20 mm TL after 31, 28, 22, 19, and 21 days of rearing, respectively (Fig. 2). As mentioned (Materials and Methods), difficulties with cleaning the cages, food supplementation to larvae and invasion of ectoparasites, together with damage of one of the cages and partial loss of fish, reduced our confidence in the data concerning survival and growth rates in the latter part of the experiment - in the period following attainment of mean TL of 20 mm in the five groups of larvae introduced into the lake cages. The results obtained (Table 2) are considered approximate. TABLE 2 Water temperature, duration of cage rearing, and final length and weight of C. albula larvae hatched and stocked at different times between 16 April 1979, and 18 May 1979 (see Table 1 for identification of Al-3 and Bl-2) Source

Date of hatching and stocking

Duration of cage rearing (days)

Water Survival temperature (%) during rearing period (“C)

Al A2 A3

23 April 9 May 18 May

51 33 29

5.5-22.8 8.6-22.8 14.5-22.8

Bl B2

17 April 1 May

52 47

5.4-22.8 7.5-22.8

Final dimensions of fish Total length (mm)

Wet weight (9)

60 -a 39

38.84 33.09 24.89

0.3875 0.2415 0.1065

64 48

36.01 35.85

0.3660 0.3305

aNo data because of damage to cage.

DISCUSSION

In the second half of the experiment the temperature of the lake surface water rose to 20-23°C (Fig. 1). Such temperatures are higher than optimal for Coregoninae: the preferred temperature for C. clupeaformis is 12.7”C (Ferguson, 1958), for C. urtedii it is in the range 13-18°C (McCormick et al., 1971), for C. lauuretus 8.0--15.4% (Coutant, 1977), and for C. autumn& 11.5-15.4”C (Fechhelm et al., 1983). Maximum temperatures observed in our experiment were close to the upper thermal limit for Coregoninae, reported for C. artedii as 21-26°C (Edsall and Colby, 1970), for C. hoyi as 26.75% (Edsall et al., 1970), and for C. clupeuformis as 20.626.6% (Edsall and Rottiers, 1976). Though young Coregoninae are believed to be more tolerant of high temperatures (Colby and Brooke, 1969), it is still possible that at 20-23°C the mortality rate of C. ulbulu larvae increased significantly (McCormick et al., 1971), especially because the larvae could not migrate into deeper and cooler water layers (Szypula, 1970).

202

After hatching, the morphological and anatomical features of teleost larvae continue to develop. Differentiation of the alimentary tract (Stroband and Dabrowski, 1979; MPhr et al., 1983), improvement in swimming ability (Batty, 1984), development of schooling behaviour (Volkova, 1976; Kawamura and Hara, 1980) and sensory organs (Blaxter et al., 1983; Branchek, 1984) are examples of major changes that occur in teleost larvae as they metamorphose to the juvenile stage. The appearance of a given stage of development is correlated with fish size rather than age (Grudniewski, 1970). Hence, the above-mentioned features, which enhance the larva’s chances for survival, should appear sooner when fish larvae grow faster. In other words, the period of greatest vulnerability would be shorter in larvae growing in better environmental conditions, primarily at optimal temperatures and food densities. Higher temperatures increase the feeding activity of larvae and they begin external feeding earlier in ontogeny (Braum, 1967), the utilization of food for growth begins earlier (Heming et al., 1982), and the instantaneous growth rate of larvae markedly increases (McCormick et al., 1971). Furthermore, at higher food concentrations fish larvae tend to select larger prey organisms (Rajasilta and Vuorinen, 1983), gross growth efficiency is higher (Laurence, 1977), larvae grow faster (Korovina et al., 1975) and survival increases as does the growth rate (Laurence, 1977). When hatching is delayed, larvae are stocked into waters with higher temperature and more abundant food. All of these factors enhance their growth rate, with the result that the successive batches of vendace larvae reached 20 mm total length in progressively shorter time periods. Assuming that C. albukr fry of 20 mm TL have already passed metamorphosis (Fliichter, 1980), one can postulate that faster growing larvae metamorphose faster and spend less time in the unfavourable larval phase when they are potential prey for numerous predators (Lindstriim, 1962; Eltsova, 1976). From this viewpoint, the technique of delaying vendace hatching should result in improved environmental conditions for larval growth, and so enhanced survival to the juvenile stage, which is considered to be more resistant to predators and unfavourable environmental conditions. On the other hand, vendace hatching should not be delayed excessively, because of the danger of high egg mortality during acclimation to the high water temperature of the advancing season (trial A3, Table 1) and also because larvae would experience unusual and perhaps unsuitable asynchronous ecological situations in the lake - such as too high temperature (cage 5, Fig. 2), parasites, new predators, and shortening of their first growing season. Numerous investigations have shown that rotifers are not accessible to Coregoninae larvae, whereas nauplii and copepodites are always accepted as their first food (Marciak, 1979, Fliichter, 1980; Teska and Behmer, 1981; Dabrowski et al., 1984). Taking this into account, Coregoninae larvae should

203

be stocked into lakes as soon as the water temperature nauplii and copepodites allow rapid growth.

and the quantity

of

ACKNOWLEDGEMENTS

The investigation Poland.

was financed

by the Inland Fisheries Institute

in Olsztyn,

REFERENCES Batty, R.S., 1984. Development of swimming movements and musculature of larval herring (Clupea harengus). J. Exp. Biol., 110: 217-229. Bernatowicz, S., Dembiriski, W. and Radziej, J., 1975. Vendace. PWRiL, Warsaw, 284 pp. (in Polish). Blaxter, J.H.S., Gray, J.A.B. and Best, A.C.G., 1983. Structure and development of the free neuromasts and lateral line system of the herring. J. Mar. Biol. Assoc. U.K., 63: 247-260. Branchek, T., 1984. The development of photoreceptors in the zebrafish, Brachydanio rerio. II. Function. J. Comp. Neurol., 224: 116-122. Braum, E., 1967. The survival of fish larvae with reference to their feeding behaviour and the food supply. In: SD. Gerking (Editor), The Biological Basis of Freshwater Fish Production. Blackwell Scientific Publications, Oxford and Edinburgh, pp. 113131. Budych, J., 1971. Coregonus albula of Sierakow Lakeland. Gospod. Rybna, 2: 8-10 (in Polish). Christie, W.J., 1963. Effects of artificial propagation and the weather on recruitment in the Lake Ontario whitefish fishery. J. Fish. Res. Board Can., 20: 597-646. Colby, P.J. and Brooke, L.T., 1969. Cisco (Coregonus ortedii) mortalities in a southern Michigan Lake, July 1968. Limnol. Oceanogr., 14: 958-960. Coutant, C.C., 1977. Compilation of temperature preference data. J. Fish. Res. Board Can., 34: 739-745. Dabrowski, K., 1975. Point of no return in the early life of fishes. An energetic attempt to define the food minimum. Wiad. Ekol., 21: 277-293 (in Polish with English summary). Dabrowski, K., Murawska, E., Terlecki, J. and Wielgosz, S., 1984. Studies on the feeding of Coregonus pollan (Thompson) alevins and fry in Lough Neagh. Int. Rev. Ges. Hydrobiol., 69: 529-540. Dembinski, W. and Falkowski, S., 1983. Rearing of young forms of vendace (Coregonus albula L.), lake whitefish (Coregonus tauaretus L.) and peled (Coregonus peled Gmel.) in surface lake cages. Rocz. Nauk Roln., H-100-1: 7-55 (in Polish with English summary). Edsall, T.A. and Colby, P.J., 1970. Temperature tolerance of young-of-the-year cisco, Coregonus artedii. Trans. Am. Fish. Sot., 99: 526-531. Edsall, T.A. and Rottiers, D.V., 1976. Temperature tolerance of young-of-the-year lake whitefish, Coregonus clupeaformis. J. Fish. Res. Board Can., 33: 177-180. Edsall, T.A., Rottiers, D.V. and Brown, E.H., 1970. Temperature tolerance of bloater (Coregonus hoyi). J. Fish. Res. Board Can., 27: 2047-2052. Einsele, W., 1963. Problems of fish-larvae survival in nature and the rearing of economically important middle European freshwater fishes. Calif. Coop. Oceanic Fish. Invest. Rep., 10: 24-30.

204 1976. Mortality of hatchery-reared larval omul Coregonus autumnalis in Lake Baikal due to predation by common fish species. Vopr. Ikhtiol., 16: 1069-1075 (in Russian). Fechhelm, R.G., Neill, W.H. and Gallaway, B.J., 1983. Temperature preference of juvenile Arctic cisco (Coregonus autumnalis) from the Alaska Beaufort Sea. Biol. Pap. Univ. Alaska, 21: 24-38. Ferguson, R.G., 1958. The preferred temperature of fish and their midsummer distribution in temperate lakes and streams. J. Fish. Res. Board Can., 15: 607-624. Fliichter, J., 1980. Review of the present knowledge of rearing whitefish (Coregonidae) larvae. Aquaculture, 19: 191-208. Gliwicz, Z.M., 1977. Food size selection and seasonal succession of filter feeding zooplankton in an eutrophic lake. Ekol. Pol., 25: 179-225. Grudniewski, C., 1970. Formation of scales in Coregonus albula L. Rocz. Nauk Roln., 92-H-4: 17-25 (in Polish with English summary). Heming, T.A., McInerney, J.E. and Alderdice, D.F., 1982. Effect of temperature on initial feeding in alevins of chinook salmon (Oncorhynchus tshawytscha). Can. J. Fish. Aquat. Sci., 39: 1554-1562. Kawamura, G. and Hara, S., 1980. The optomotor reaction of milkfish larvae and juveniles. Bull. Jpn. Sot. Sci. Fish., 46: 929-932. Korovina, V.M., Lebedeva, L.I., Maximova, L.P. and Privodina, V.P., 1975. Feeding, growth and development of the chir larvae under different environmental conditions. Izv. Gos. NIORCh, 104: 152-179 (in Russian). Laurence, G.C., 1977. A bioenergetic model for the analysis of feeding and survival potential of winter flounder, Pseudopleuronectes americanus, larvae during the period from hatching to metamorphosis. Fish. Bull., 75: 529-546. Lindstrom, T., 1962. Life history of whitefish young (Coregonus) in two lake reservoirs. Rep. Inst. Freshwater Res. Drottningholm, 44: 113-144. Luczynski, M., 1984a. Improvement in the efficiency of stocking lakes with larvae of Coregonus albula L. by delaying hatching. Aquaculture, 41: 99-111. Luczynski, M., 1984b. A technique for delaying embryogenesis of vendace (Coregonus albuia L.) eggs in order to synchronize mass hatching with optimal conditions for lake stocking. Aquaculture, 41: 113-117. Luczynski, M., 1985. Survival of Coregonus albula (L.) (Teleostei) embryos incubated at different thermal conditions. Hydrobiologia, 121: 51-58. Mahr, K., Grabner, M., Hofer, R. and Moser, H., 1983. Histological and physiological development of the stomach in Coregonus sp. Arch. Hydrobiol., 98: 344-353. Marciak, Z., 1979. Food preference of juveniles of three coregonid species reared in cages. In: E. Styczyriska-Jurewicz, T. Backiel, E. Jaspers and G. Persoone (Editors), Cultivation of Fish Fry and its Live Food. European Mariculture Society, Special Eltsova,

V.N.,

migratorius

Publication No. 4, pp. 127-137. 1971. Temperature requirements for McCormick, J.H., Jones, B.R. and Syrett, R.F., growth and survival of larval ciscos (Coregonus artedii). J. Fish. Res. Board Can., 28: 924-927. Felchenerbriitung mit kiinstlich abgekiihltem Wasser im UmwalzNiimann, W., 1953. verfahren. Z. Fisch. (N.F.), 2: 83-92. Ungewollte und gezielte Eingriffe in die Populationsdynamik der Niimann, W., 1967. Blaufelchen. Arch. Fisch., 18: 12-24. Numann, W., 1970. The “Blaufelchen” of Lake Constance (Coregonus wartmanni) under negative and positive Biology of Coregonid

influence of man. In: C.C. Lindsay and C.S. Woods (Editors), Fishes. University of Manitoba Press, Winnipeg, Man., pp. 531-

552. Patalas, K., 1963. Seasonal changes in pelagic crustacean plankton in six lakes of Wegorzewo district, Rocz. Nauk Roln., 82-B-2: 210-234 (in Polish with English summary).

205 Rajasilta, M. and Vuorinen, I., 1983. A field study of prey selection in planktivorous fish larvae. Oecologia (Berlin), 59: 65-68. Stroband, H.W.J. and Dabrowski, K.R., 1979. Morphological and physiological aspects of the digestive system and feeding in fresh-water fish larvae. Nutrition de Poissons. CNERNA, Paris, Vol. 5, pp. 355-376. Szczerbowski, J.A. and Mamcarz, A., 1984. Rearing of coregonid fishes (Coregonidae) in illuminated lake cages. II. Environmental conditions during fish rearing. Aquaculture, 40: 147-161. Szypula, J., 1970. Growth and distribution of Coregonus albulo L. fry in Leginskie and Wydrynskie Lakes. Rocz. Nauk Roln., H-92-3: 45-60 (in Polish with English summary). Teska, J.D. and Behmer, D.J., 1981. Zooplankton preference of larval lake whitefish. Trans. Am. Fish. Sot., 110: 459-461. Volkova, L.A., 1976. The role of the school in the formation of defence reflexes in juvenile Coregonus autumnalis migrutorius from Lake Baikal. Vopr. Ikhtiol., 16(3): 540-545 (in Russian).