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Age and growth of Ray’s bream (Brama brama) from the south of Portugal
Fisheries Research 51 (2001) 343±347
Age and growth of Ray's bream (Brama brama) from the south of Portugal Carina Lobo, Karim Erzini* Centro de CieÃncias do Mar (CCMAR), Universidade do Algarve, 8000 Faro, Portugal
Abstract Age and growth of 234 Brama brama Bonnaterre (1788) (Pisces: Bramidae) caught by semi-pelagic longline off the south coast of Portugal (Algarve) was studied using otoliths for age determination. Samples consisted of ®sh varying in total length from 32 to 56 cm and in weight from 332 to 2032 g. Age classes from III to XII were represented in the catches. The von Bertalanffy growth curve was ®tted and the length/weight relationship was calculated. # 2001 Elsevier Science B.V. All rights reserved. Keywords: Atlantic promfret; Ray's bream; Brama brama; Age and growth; Portugal
1. Introduction Ray's bream or Atlantic pomfret (Brama brama) is a cosmopolitan species which is particularly abundant in the eastern Atlantic, ranging from the Faroes and the North Sea to South Africa (RodrõÂguez, 1980; Santos, 1982; Last and Baron, 1994). It is generally found on the continental slope, undertaking daily vertical migrations and seasonal migrations to and from more temperate waters (Mead, 1972; Haedrich, 1986; Bauchot, 1987). In the North Atlantic, Ray's bream is a seasonally important ®sheries resource, with a directed ®shery in Galicia, northwestern Spain (RodrõÂguez, 1980). It is also ®shed in Portugal and off northwest Africa (Mead and Headrich, 1965; Mead, 1972; Santos, 1982; Erzini et al., 2001). B. brama is caught mainly by hook and line gear; with pelagic and semi-pelagic longline as *
Corresponding author. Tel.: 351-289-800-100; fax: 351-289-818-353. E-mail address: [email protected] (K. Erzini).
well as electric reels and handlines. Off the south coast of Portugal, it is the second most abundant commercial species in the hake (Merluccius merluccius) semipelagic longline ®shery (Erzini et al., 2001). Information on the biology, ecology and population dynamics of B. brama is scarce (Mead, 1972; RodrõÂguez, 1980; Santos, 1982). Only RodrõÂguez (1980) studied the age and growth with little success. Existing data mainly concerns feeding habits, reproduction, parasitism, migrations, commercial importance and ¯uctuation in abundance. In this study, age and growth of Ray's bream caught off the south coast of Portugal was studied using the sagittal otoliths. 2. Materials and methods A total of 234 individuals were obtained as a bycatch in the seasonal (between April and October 1997) hake longline ®shery off southern Portugal (Algarve) at depths from 200 to 600 m. In the laboratory, total length (TL), standard length (SL), and fork
0165-7836/01/$ ± see front matter # 2001 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 5 - 7 8 3 6 ( 0 1 ) 0 0 2 5 8 - 2
344
C. Lobo, K. Erzini / Fisheries Research 51 (2001) 343±347
length (FL) were measured to the nearest 0.5 cm below and each ®sh was weighed to the nearest gram. Not all the ®sh were sexed because of the poor condition of the gonads when the ®sh were landed. The sagittal otoliths were extracted. The otoliths were washed in distilled water, dried and stored in individual envelopes for later reading. The otoliths of this species are small, with a large and opaque nucleus, which is characteristic of ®sh which spawn in winter or early spring (Penttila and Dery, 1988). In order to minimise errors, a standardised methodology was used for de®ning the limits of the nucleus and the growth rings (Leta and Keim, 1982). The presence of false rings was noted in some otoliths and these were not used for the growth parameter estimation. Two independent readings of one otolith from each ®sh were carried out with compound microscope at 1.6 and 2.5 magni®cation and with re¯ected light.
An age±length key was constructed and the parameters of the von Bertalanffy growth equation estimated by non-linear least-squares regression (SAS Institute Inc., 1988). In addition, the weight±length relationship W aLb where W is total weight (g) and L is TL (cm) was fitted to the log-transformed data: log W log a b log L. The relationship between TL and FL was determined by simple linear regression. 3. Results The length±frequency distribution of the ®sh used in the study is shown in Fig. 1. The ®sh sampled ranged from 32.4 (332 g) to 55.8 cm (2032 g). The weight±length relationship was W 0:00511 L 3.185
Fig. 1. Size frequency distribution of the fish used in the study.
Fig. 2. Observed weight±length values and fitted curve.
C. Lobo, K. Erzini / Fisheries Research 51 (2001) 343±347
345
Fig. 3. Relationship between TL and FL.
(Fig. 2). The relationship between TL and FL is shown in Fig. 3. Of the 234 ®sh sampled, 19 (8.1%) could not be aged. The age±length key is given in Table 1. As can be seen, age classes from III to XII were present, with the majority of the ®sh in age classes VI±VIII, and only one ®sh in the youngest and oldest age classes. The length distributions by age were not normal and may indicate selectivity due to hook size or some other factor. The observed age±length data and the ®tted von Bertalanffy curve are given in Fig. 4. The estimated
parameters were: t0 ÿ3:854, K 0:084, and L1 70:5, giving the following equation: Lt 70:5 1 ÿ eÿ0:084 t3:854
4. Discussion This study was carried out using ®sh sampled from the seasonal (spring±autumn) hake longline ®shery, which is characterised by the capture of large, adult ®sh. Although hook selectivity may be a factor, the
Table 1 Age±length key for B. brama Total length (cm)
Age class III
[32±34[ [34±36[ [36±38[ [38±40[ [40±42[ [42±44[ [44±46[ [46±48[ [48±50[ [50±52[ [52±54[ [54±56[ N Mean TL Standard deviation
1
1 32.4
Total number IV 2 4 1
7 36.77 1.52
V
7 5 6 2
20 38.76 1.75
VI
1 15 15 9 4
44 40.66 2.01
VII
13 20 12 4 7
56 41.98 2.31
VIII
13 12 8 7 8 5
53 43.04 3.2
IX
3 2 2 8 6
21 46.41 2.76
X
3 5
8 49.9 0.59
XI
1 2 1 4 52.7 1.57
XII
1 1 55.8
1 2 12 47 56 33 17 23 14 6 2 2 215
346
C. Lobo, K. Erzini / Fisheries Research 51 (2001) 343±347
Fig. 4. Observed age±length data and fitted von Bertalanffy growth curve.
lack of small or juvenile individuals is more likely to be due to their absence in the Algarve region, since spawning takes place further south during the winter in the eastern Atlantic (Mead, 1972; Haedrich, 1986; Bauchot, 1987), at water temperatures greater than 208C. The largest ®sh are found at the greatest depths (Morales-Nin, 1991). The age estimates could not be validated because there were too few ®sh, especially small ®sh, for the use of length based methods and the lack of a complete seasonal coverage precluded marginal increment studies. The lack of small and younger individuals and the lack of information on any sex related differences in growth rate has important implications for growth parameter estimation. As can be seen in Fig. 4 and by the relatively large value of ÿ3.854 for the parameter t0, the ®tted von Bertalanffy growth curve probably does not accurately describe growth during the ®rst three years of life. Analysis of the data suggests that growth during these ®rst few years is probably relatively fast, slowing down during the adult stage. Thus, a higher growth rate would certainly be estimated if age±length data for the youngest age classes were available. Nevertheless, the ®tted von Bertalanffy growth equation adequately describes the growth of the individuals present in Portuguese waters, indicating that growth during the adult part of the life cycle is slow K 0:085. The estimated L1 of 70.5 cm TL is in accordance with the reported maximum length of 70 cm SL (QueÂro, 1984; Haedrich, 1986; Bauchot, 1987).
Although Ray's bream is an established resource in southern European waters and a potentially important one elsewhere (Last and Baron, 1994), there is little information on its population dynamics. The only other age and growth study, for ®sh from northwestern Spain, was inconclusive (RodrõÂguez, 1980). The most closely related species, the Paci®c pomfret (Brama japonica), found in the North Paci®c, has been better studied and provides a useful comparison for Ray's bream. For B. japonica, maximum ages of 3 (Bigelow et al., 1995), 6±7 (Pearcy et al., 1993) and 9 (Savinykh and Vlasova, 1994) have been reported, with the differences possibly due to the existence of sub-populations (Savinykh and Vlasova, 1994). Several authors reported a period of fast growth during the ®rst few years of life (Shimazaki, 1989; Pearcy et al., 1993). References Bauchot, M.L., 1987. Poissons osseaux. In: Fisher, W., Schneider, M., Bauchot, M.L. (Eds.), Fishes FAO d' identification des espeÁces pour les besoins de la peÃche, MediterraneÂe et Mer Noire, zone de peÃche 37, Vertebres, Vol. II. FAO, Rome, pp. 1000±1001. Bigelow, K.A., Jones, J.T., DiNardo, G.T., 1995. Growth of the Pacific pomfret, Brama japonica: a comparison between otolith and length±frequency (MULTIFAN) analysis. Can J. Fish. Aquat. Sci. 52, 2747±2756. Erzini, K., GoncËalves, J.M.S., Bentes, L., Lino, P.G., Ribeiro, J., 2001. The hake deepwater semi-pelagic (``pedra-bola'') longline fishery in the Algarve (southern Portugal). Fish. Res. 51, 325±334.
C. Lobo, K. Erzini / Fisheries Research 51 (2001) 343±347 Haedrich, R.L., 1986. Bramidae. In: Whitehead, P.J., Bauchot, M.L., Hureau, J.C., Nielsen, J., Tortonese, E. (Eds.), Fishes of the Northeastern Atlantic and Mediterranean, Vol. II. UNESCO, Paris, pp. 847±853. Last, P., Baron, M., 1994. Rays bream Ð a new pelagic fishery? Aus. Fish. Suppl. 19±22. Leta, H.R., Keim, A., 1982. Lectura de edades en otolitos de peces teleosteos. Instituto Nacional de Pesca, Montevideo, Uruguay, Informe Tecnico 30, pp.1±36. Mead, G.W., 1972. Bramidae. Dana Report 81, 1±166. Mead, G.W., Headrich, R.L., 1965. The distribution of the oceanic fish Brama brama. Bull. Mus. Comp. Zool., Harvard Univ. 134, 29±68. Morales-Nin, B., 1991. ParaÂmetros bioloÂgicos del salmonete de roca Mullus surmuletos (L. 1758) en Mallorca. Bol. Inst. Esp. Oceanogr. 7 (2), 139±147. Pearcy, W.G., Fisher, J.P., Yoklavich, M.M., 1993. Biology of the Pacific pomfret (Brama japonica) in the North Pacific Ocean. Can. J. Fish. Aquat. Sci. 50, 2608±2624.
347
Penttila, J., Dery, L.M., 1988. Age determination methods for Northwest Atlantic species. NOAA Technical Report NMFS72, US Department of Commerce. QueÂro, J.C., 1984. Les Poissons de Mer des PeÃches FrancËaises. Jacques Graucher (Ed.), Paris, 394 pp. RodrõÂguez, A.V., 1980. Sobre la biologõÂa y pesca de la castanÄeta (Brama brama). Inv. Pesq. 44, 241±252. Santos, A.J.F.A., 1982. ContribuicËaÄo para o Conhecimento e AvaliacËaÄo do Stock de Brama brama no AtlaÃntico Nordeste. RelatoÂrio de EstaÂgio CientõÂfico do Curso de Biologia, Faculdade de CieÃncias de Lisboa. SAS Institute Inc., 1988. SAS/STAT User's Guide, Release 6.03 Edition, Cary, NC. Savinykh, V.F., Vlasova, L.V., 1994. The Length±age structure and growth rate of the Pacific pomfret, Brama japonica (Bramidae). J. Ichthyol. 34, 97±107. Shimazaki, K., 1989. Ecological studies of the pomfret (Brama japonica) in the North Pacific Ocean. Can. Spec. Publ. Aquat. Sci. 108, 195±205.
Age and growth of Ray's bream (Brama brama) from the south of Portugal Carina Lobo, Karim Erzini* Centro de CieÃncias do Mar (CCMAR), Universidade do Algarve, 8000 Faro, Portugal
Abstract Age and growth of 234 Brama brama Bonnaterre (1788) (Pisces: Bramidae) caught by semi-pelagic longline off the south coast of Portugal (Algarve) was studied using otoliths for age determination. Samples consisted of ®sh varying in total length from 32 to 56 cm and in weight from 332 to 2032 g. Age classes from III to XII were represented in the catches. The von Bertalanffy growth curve was ®tted and the length/weight relationship was calculated. # 2001 Elsevier Science B.V. All rights reserved. Keywords: Atlantic promfret; Ray's bream; Brama brama; Age and growth; Portugal
1. Introduction Ray's bream or Atlantic pomfret (Brama brama) is a cosmopolitan species which is particularly abundant in the eastern Atlantic, ranging from the Faroes and the North Sea to South Africa (RodrõÂguez, 1980; Santos, 1982; Last and Baron, 1994). It is generally found on the continental slope, undertaking daily vertical migrations and seasonal migrations to and from more temperate waters (Mead, 1972; Haedrich, 1986; Bauchot, 1987). In the North Atlantic, Ray's bream is a seasonally important ®sheries resource, with a directed ®shery in Galicia, northwestern Spain (RodrõÂguez, 1980). It is also ®shed in Portugal and off northwest Africa (Mead and Headrich, 1965; Mead, 1972; Santos, 1982; Erzini et al., 2001). B. brama is caught mainly by hook and line gear; with pelagic and semi-pelagic longline as *
Corresponding author. Tel.: 351-289-800-100; fax: 351-289-818-353. E-mail address: [email protected] (K. Erzini).
well as electric reels and handlines. Off the south coast of Portugal, it is the second most abundant commercial species in the hake (Merluccius merluccius) semipelagic longline ®shery (Erzini et al., 2001). Information on the biology, ecology and population dynamics of B. brama is scarce (Mead, 1972; RodrõÂguez, 1980; Santos, 1982). Only RodrõÂguez (1980) studied the age and growth with little success. Existing data mainly concerns feeding habits, reproduction, parasitism, migrations, commercial importance and ¯uctuation in abundance. In this study, age and growth of Ray's bream caught off the south coast of Portugal was studied using the sagittal otoliths. 2. Materials and methods A total of 234 individuals were obtained as a bycatch in the seasonal (between April and October 1997) hake longline ®shery off southern Portugal (Algarve) at depths from 200 to 600 m. In the laboratory, total length (TL), standard length (SL), and fork
0165-7836/01/$ ± see front matter # 2001 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 5 - 7 8 3 6 ( 0 1 ) 0 0 2 5 8 - 2
344
C. Lobo, K. Erzini / Fisheries Research 51 (2001) 343±347
length (FL) were measured to the nearest 0.5 cm below and each ®sh was weighed to the nearest gram. Not all the ®sh were sexed because of the poor condition of the gonads when the ®sh were landed. The sagittal otoliths were extracted. The otoliths were washed in distilled water, dried and stored in individual envelopes for later reading. The otoliths of this species are small, with a large and opaque nucleus, which is characteristic of ®sh which spawn in winter or early spring (Penttila and Dery, 1988). In order to minimise errors, a standardised methodology was used for de®ning the limits of the nucleus and the growth rings (Leta and Keim, 1982). The presence of false rings was noted in some otoliths and these were not used for the growth parameter estimation. Two independent readings of one otolith from each ®sh were carried out with compound microscope at 1.6 and 2.5 magni®cation and with re¯ected light.
An age±length key was constructed and the parameters of the von Bertalanffy growth equation estimated by non-linear least-squares regression (SAS Institute Inc., 1988). In addition, the weight±length relationship W aLb where W is total weight (g) and L is TL (cm) was fitted to the log-transformed data: log W log a b log L. The relationship between TL and FL was determined by simple linear regression. 3. Results The length±frequency distribution of the ®sh used in the study is shown in Fig. 1. The ®sh sampled ranged from 32.4 (332 g) to 55.8 cm (2032 g). The weight±length relationship was W 0:00511 L 3.185
Fig. 1. Size frequency distribution of the fish used in the study.
Fig. 2. Observed weight±length values and fitted curve.
C. Lobo, K. Erzini / Fisheries Research 51 (2001) 343±347
345
Fig. 3. Relationship between TL and FL.
(Fig. 2). The relationship between TL and FL is shown in Fig. 3. Of the 234 ®sh sampled, 19 (8.1%) could not be aged. The age±length key is given in Table 1. As can be seen, age classes from III to XII were present, with the majority of the ®sh in age classes VI±VIII, and only one ®sh in the youngest and oldest age classes. The length distributions by age were not normal and may indicate selectivity due to hook size or some other factor. The observed age±length data and the ®tted von Bertalanffy curve are given in Fig. 4. The estimated
parameters were: t0 ÿ3:854, K 0:084, and L1 70:5, giving the following equation: Lt 70:5 1 ÿ eÿ0:084 t3:854
4. Discussion This study was carried out using ®sh sampled from the seasonal (spring±autumn) hake longline ®shery, which is characterised by the capture of large, adult ®sh. Although hook selectivity may be a factor, the
Table 1 Age±length key for B. brama Total length (cm)
Age class III
[32±34[ [34±36[ [36±38[ [38±40[ [40±42[ [42±44[ [44±46[ [46±48[ [48±50[ [50±52[ [52±54[ [54±56[ N Mean TL Standard deviation
1
1 32.4
Total number IV 2 4 1
7 36.77 1.52
V
7 5 6 2
20 38.76 1.75
VI
1 15 15 9 4
44 40.66 2.01
VII
13 20 12 4 7
56 41.98 2.31
VIII
13 12 8 7 8 5
53 43.04 3.2
IX
3 2 2 8 6
21 46.41 2.76
X
3 5
8 49.9 0.59
XI
1 2 1 4 52.7 1.57
XII
1 1 55.8
1 2 12 47 56 33 17 23 14 6 2 2 215
346
C. Lobo, K. Erzini / Fisheries Research 51 (2001) 343±347
Fig. 4. Observed age±length data and fitted von Bertalanffy growth curve.
lack of small or juvenile individuals is more likely to be due to their absence in the Algarve region, since spawning takes place further south during the winter in the eastern Atlantic (Mead, 1972; Haedrich, 1986; Bauchot, 1987), at water temperatures greater than 208C. The largest ®sh are found at the greatest depths (Morales-Nin, 1991). The age estimates could not be validated because there were too few ®sh, especially small ®sh, for the use of length based methods and the lack of a complete seasonal coverage precluded marginal increment studies. The lack of small and younger individuals and the lack of information on any sex related differences in growth rate has important implications for growth parameter estimation. As can be seen in Fig. 4 and by the relatively large value of ÿ3.854 for the parameter t0, the ®tted von Bertalanffy growth curve probably does not accurately describe growth during the ®rst three years of life. Analysis of the data suggests that growth during these ®rst few years is probably relatively fast, slowing down during the adult stage. Thus, a higher growth rate would certainly be estimated if age±length data for the youngest age classes were available. Nevertheless, the ®tted von Bertalanffy growth equation adequately describes the growth of the individuals present in Portuguese waters, indicating that growth during the adult part of the life cycle is slow K 0:085. The estimated L1 of 70.5 cm TL is in accordance with the reported maximum length of 70 cm SL (QueÂro, 1984; Haedrich, 1986; Bauchot, 1987).
Although Ray's bream is an established resource in southern European waters and a potentially important one elsewhere (Last and Baron, 1994), there is little information on its population dynamics. The only other age and growth study, for ®sh from northwestern Spain, was inconclusive (RodrõÂguez, 1980). The most closely related species, the Paci®c pomfret (Brama japonica), found in the North Paci®c, has been better studied and provides a useful comparison for Ray's bream. For B. japonica, maximum ages of 3 (Bigelow et al., 1995), 6±7 (Pearcy et al., 1993) and 9 (Savinykh and Vlasova, 1994) have been reported, with the differences possibly due to the existence of sub-populations (Savinykh and Vlasova, 1994). Several authors reported a period of fast growth during the ®rst few years of life (Shimazaki, 1989; Pearcy et al., 1993). References Bauchot, M.L., 1987. Poissons osseaux. In: Fisher, W., Schneider, M., Bauchot, M.L. (Eds.), Fishes FAO d' identification des espeÁces pour les besoins de la peÃche, MediterraneÂe et Mer Noire, zone de peÃche 37, Vertebres, Vol. II. FAO, Rome, pp. 1000±1001. Bigelow, K.A., Jones, J.T., DiNardo, G.T., 1995. Growth of the Pacific pomfret, Brama japonica: a comparison between otolith and length±frequency (MULTIFAN) analysis. Can J. Fish. Aquat. Sci. 52, 2747±2756. Erzini, K., GoncËalves, J.M.S., Bentes, L., Lino, P.G., Ribeiro, J., 2001. The hake deepwater semi-pelagic (``pedra-bola'') longline fishery in the Algarve (southern Portugal). Fish. Res. 51, 325±334.
C. Lobo, K. Erzini / Fisheries Research 51 (2001) 343±347 Haedrich, R.L., 1986. Bramidae. In: Whitehead, P.J., Bauchot, M.L., Hureau, J.C., Nielsen, J., Tortonese, E. (Eds.), Fishes of the Northeastern Atlantic and Mediterranean, Vol. II. UNESCO, Paris, pp. 847±853. Last, P., Baron, M., 1994. Rays bream Ð a new pelagic fishery? Aus. Fish. Suppl. 19±22. Leta, H.R., Keim, A., 1982. Lectura de edades en otolitos de peces teleosteos. Instituto Nacional de Pesca, Montevideo, Uruguay, Informe Tecnico 30, pp.1±36. Mead, G.W., 1972. Bramidae. Dana Report 81, 1±166. Mead, G.W., Headrich, R.L., 1965. The distribution of the oceanic fish Brama brama. Bull. Mus. Comp. Zool., Harvard Univ. 134, 29±68. Morales-Nin, B., 1991. ParaÂmetros bioloÂgicos del salmonete de roca Mullus surmuletos (L. 1758) en Mallorca. Bol. Inst. Esp. Oceanogr. 7 (2), 139±147. Pearcy, W.G., Fisher, J.P., Yoklavich, M.M., 1993. Biology of the Pacific pomfret (Brama japonica) in the North Pacific Ocean. Can. J. Fish. Aquat. Sci. 50, 2608±2624.
347
Penttila, J., Dery, L.M., 1988. Age determination methods for Northwest Atlantic species. NOAA Technical Report NMFS72, US Department of Commerce. QueÂro, J.C., 1984. Les Poissons de Mer des PeÃches FrancËaises. Jacques Graucher (Ed.), Paris, 394 pp. RodrõÂguez, A.V., 1980. Sobre la biologõÂa y pesca de la castanÄeta (Brama brama). Inv. Pesq. 44, 241±252. Santos, A.J.F.A., 1982. ContribuicËaÄo para o Conhecimento e AvaliacËaÄo do Stock de Brama brama no AtlaÃntico Nordeste. RelatoÂrio de EstaÂgio CientõÂfico do Curso de Biologia, Faculdade de CieÃncias de Lisboa. SAS Institute Inc., 1988. SAS/STAT User's Guide, Release 6.03 Edition, Cary, NC. Savinykh, V.F., Vlasova, L.V., 1994. The Length±age structure and growth rate of the Pacific pomfret, Brama japonica (Bramidae). J. Ichthyol. 34, 97±107. Shimazaki, K., 1989. Ecological studies of the pomfret (Brama japonica) in the North Pacific Ocean. Can. Spec. Publ. Aquat. Sci. 108, 195±205.