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Home , Caranx, Cocinero, Green jack

of the caballus (Osteichytes: ) in Las Perlas Archipelago, Pacific

James M. Mair1, Roberto Cipriani2, Hector M. Guzman3* & David Usan1 1. Centre for Marine Biodiversity and Biotechnology, School of Life Sciences, Heriot-Watt University, Edinburgh EH14 4AS, Scotland, UK; [email protected], [email protected] 2. Departament of Biological Science, State University, Fullerton, US; [email protected] 3. Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancon, Panama; [email protected] * Corresponding author

Received 29-viii-2011. Corrected 10-iii-2012. Accepted 12-iv-2012.

Abstract: Green Jacks, Caranx caballus, are distributed along the Eastern Pacific . In Panama, C. caballus was heavily fished around Las Perlas Archipelago to sustain local markets until 2007, when the archipelago was declared a marine protected area. This first study in Panama, analyzed a sample of 4 990 individuals from Las Perlas, obtained monthly from June 2005 to June 2006, from landings at the central market. Average total length was 36.1±6.4cm and optimum length 38.9cm. Approximately 68% of fish lengths were within ±10% of the optimal length but only six (15%) were considered mega-spawners. The von Bertalanffy parameters describe a long-lived and fast growing , while mortality rates revealed that C. caballus is under high fishing pres- sure. Standard length at which half of the population is mature was 38.8cm, and the size at which individuals matured massively, 33cm. Only 10-13% of the fish were immature. C. caballus reproduces two to three times per year, with peaks in December, April, and probably September, and recruits to the population at least twice per year. Catch per unit effort (CPUE) was best predicted by minimum annual values of the Multivariate ENSO/ LNSO Index (MEI) (R2=0.54). Results show that C. caballus in Pacific Panama is overfished. We recommend the raising of the minimum capture/landing size of this species in to increase the proportion of mega- spawners in the population and guarantee the sustainability of this resource. Rev. Biol. Trop. 60 (3): 1271-1288. Epub 2012 September 01.

Key words: Caranx caballus, cojinua, green jack, fishery assessment, Eastern Pacific, Panama.

Caranx caballus, Günther 1868, is a pelag- and other large predators (Bernal-Ornelas et al. ic species inhabiting coastal waters from South- 2005, Robertson & Allen 2008). ern California to Chile, the Galapagos, Cocos, Most catches of Green Jack in the Eastern Malpelo, the Revillagigedo in the East- Pacific result from unregulated, artisanal, and ern Pacific , and in the Cen- subsistence . Equipment commonly tral Pacific Ocean (Robertson & Allen 2008, used includes gill and cast nets, lines, hooks, Froese & Pauly 2010). Juveniles are found in and spinning tackles deployed from small coastal waters, (Smith-Vaniz 1995), boats or from land (Gallardo-Cabello et al. and swimming close to floating objects in the open ocean, while adults live 30 to 100m deep 2007). As these catches are consumed locally, forming schools over soft bottoms (Robertson fishing records are generally non-existent or & Allen 2008, Froese & Pauly 2010). They incomplete. In small towns, Green Jacks are feed upon , mollusks, chaetognaths, marketed in salted, dried, and smoked forms, cnidarians and such as engraulids and are often used to produce fishmeal and fish and clupeids, and are prey of , oil (Froese & Pauly 2010).

Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 60 (3): 1271-1288, September 2012 1271 In Las Perlas Archipelago, Gulf of Pan- populations fished along the shores of Colima, ama, Caranx caballus, Cojinúas, or Green Pacific (e.g. Cruz-Romero et al. 1993, Jacks, are fished using seine nets, operated Gallardo-Cabello et al. 2007). by winches from boats up to 25m long, either In this study, analyses were carried out known as bolicheros, or deployed by hand from on the length frequency distributions of Green smaller boats during fishing campaigns lasting Jacks or C. caballus obtained from the Panama from 4 to 5 days, and very occasionally 8-9 Fish Market from June 2005-June 2006, and days. After capture, Green Jacks are kept in ice these were then used to estimate stable age and transported to Mercado del Marisco, the groups, parameters of the corresponding von Fish Market in Panama City, where they are Bertalanffy’s model, longevity, and mortal- sold fresh to the public. ity rates. In addition, descriptions are given of Their relative high abundance, meat of their reproductive stages using both external poor to average quality, and lack of intermedi- gonadic features and a weight-based gonadic aries between fishermen and consumers, have index, and this information is combined with kept the Green Jack sale prices accessible growth data to determine size at the onset to people with low incomes, varying from of maturity. Finally, the association between US$0.5-1.1 in 2006 to US$3.1-3.7 in 2010 the fishing productivity and the effects of (ACODECO 2010). Green Jacks are also one the yearly upwelling event and the ENSO/ of the food items of the “basic shopping bas- LNSO in Central and South Eastern Pacific ket” (canasta básica, in Spanish), which is was assessed. used to calculate the overall cost of household and food essentials for a in Panama. MATERIALS AND METHODS In recent years, the annual production of Green Jacks in Panama has become a topic Study area and samples: Las Perlas of concern to scientists and authorities, as Archipelago, Roca Trollope, and Isla Galera, it decreased from 1 436t in 2003 to 477t in are important fishing grounds in the Gulf of 2006. As the total number of fishing boats Panama (Cipriani et al. 2008a, b, Guzman et had increased slowly in the region since 1998 al. 2008). Enclosed within a Marine Special (Anonymous 2010b), these abrupt changes in Management Zone, extending 168 771ha, the production were feared to be early signs of archipelago has 255 islands (33 153ha) of overexploitation (Anonymous 2010a). On May which Del Rey (8° 22’54.64’’ N-78° 54’20.16’’ 31 2007, the Assembly of Panama approved W) is the largest (Guzman et al. 2008). During Law N°18, banning fisheries operating with the dry season, between January and April, mechanical gears, such as those carried out Northeast trade winds create upwelling along on bolicheros, from the waters surrounding the Gulf of Panama. The warm, nutrient- Las Perlas Archipelago, and declaring these depleted water carried away from the coast waters as a Special Management Marine and by the winds is replaced by cold, nutrient-rich Coastal Zone. water (15º-20ºC) from the deep, triggering In 2008, the annual production of Green large- phytoplankton blooms that boost Jacks recovered to 1 640t. Despite the intro- the archipelago’s productivity (D’Croz et al. duction of Law N°18, which aimed to create 1991). The region also experiences the effects management plans for marine natural resources of El Niño (ENSO) and La Niña Southern in the archipelago, using the best scientific Oscillation (LNSO) (McNiven 2003, D’Croz evidence available, there was in 2010 still & O’Dea 2007). very scarce information in the region’s techni- Between June 2005 and June 2006, 4 990 cal literature on Green Jacks, such as growth, C. caballus from Mercado del Marisco were , , and population dynam- obtained: 400 fish were haphazardly selected ics. The few studies available were on the and bought every month, apart from in June

1272 Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 60 (3): 1271-1288, September 2012 2005 (200 fish) and May 2006 (790 fish). No approximation of Froese & Binohlan (2000). fish were available in November 2005 as bad Optimal fisheries should exploit fish within the weather grounded the fishing fleet. Samples approximate range LOPT ± 10%: smaller fish were analyzed, as explained in next para- are too young or immature and larger fish are graphs, in the Coastal Ecology and Conserva- mega-spawners (Froese 2004). tion Biology Laboratory at the STRI facility Length frequency histograms3 with bins of L = L . of Naos. Samples from May and June 2006 OPT ∞ M 1cm were prepared. von3 + Bertalanffy’s models were strongly biased in size and were excluded (Sparre & Venema 1998, Essingtonk et al. 2001) from growth, mortality, age structure, and in the form: maturity analyses. -k.(t-t ) . 0 (Lt - L0) = L∞ (1-e ) Biometrics, growth and mortality: Mea- were fitted to monthly histogram sets of LS surements taken were the standard (LS) and total length (L ) of all individuals using an obtained from males and females, and to T 1 Lt 1 monthly histogramt = t - sets . ln of 1 L- S and = t L -T obtained . ln (1-θ) ichthyometer, and their total wet weight (WT) to θ 0 L 0 k ( ∞ ) k the nearest ounce (transformed to grams in our from pooled samples of both sexes. analyses) using a weighing scale (BAICO, 40lb Green Jacks were assumed to start grow- max, Colombia). The relationship between L ing at lengths of 0cm (LO=0) at year 0 (tO=0), T but rounding-off errors produced small values and LS was described using a reduced major axis model (RMA) in the form: of tO. Models were fitted using the ELEFAN I procedure implemented in the software pro- W = a×Lb, gram FAO-ICLARM Fish Assessment Tools T (FiSAT II, ver. 1.2.2) (Gayanilo et al. 2005). where a and b are regression parameters. The best value of k was reported from the scan method, L∞ as the ratio of the instantaneous rate The power law equation of mortality Z and k (Powell 1979, Wetherall 1986), and the two best estimates of L∞ and k b from the surface response analysis (Sparre & WT = a×L , Venema 1998). where a and b are regression parameters and The growth performance3 index f’ was L = L . L is length, was used to describe the relation calculatedOPT as: ∞ M 3 + between LS and WT and that between LT and k WT. The model was fitted to the data using f’= log10(k) + 2×log10(L∞), non-linear weighted least-squares using the -k.(t-t ) (L - L ) = L . (1-e 0 ) statistical package R (R Development Core implementedt 0 in FiSAT∞ II, ver. 1.2.2 (Gayanilo Team 2011). Intervals of 95% confidence (CI) et al. 2005), and longevity, the time required to of parameters a and b were obtained by boot- achieve 95% of L∞, following: strapping each data set 4 999 times. Finally, we 1 Lt 1 t = t - . ln 1 - = t - . ln (1-θ) estimated LOPT following Beddington & Cooke θ 0 L 0 k ( ∞ ) k (1983) and (1992), where θ=0.95 (Taylor 1958). All chronological 3 L = L . ages were obtained from eq. 6 using parameters OPT ∞ M 3 + k from pooled data of both sexes. The age distribution and growth rate of where M is the average natural mortality (0.5 in Green Jacks were assumed to be stable, so -k.(t-t ) . 0 the current samples),(Lt - L0) L= ∞L ∞is (1-thee infinite) length, Z was approximated using length-converted k is the curvature of von Bertalanffy’s model catch curves and the methods of Jones and

(eq. 4). Also estimated was LOPT using the van Zalinge (1981), Hoenig (1982), Hoenig &

1 Lt 1 t = t - . ln 1 - = t - . ln (1-θ) Rev. Biol. Trop. (Int. J. Trop.θ Biol.0 ISSN-0034-7744)L Vol. 60 (3):0 1271-1288, September 2012 k ( ∞ ) k 1273 Lawing (1982), Beverton & Holt (1956), and was that at which the maximum values per

Ault & Erhardt (1991), and Erhardt & Ault month of IG increased abruptly. (1992). The natural mortality coefficient M was The associations between the monthly arc- estimated using the Rikhter & Efanov’s (1976) sine-transformed proportions of fully mature and Taylor’s method (1958, 1960), and Pauly´s stages and IG monthly maxima, and the monthly empirical formula (1980, 1983, 1984), using averages of sea surface temperature (SST, Cel- 27.4°C as the average surface temperature of sius degrees) and chlorophyll concentrations the Gulf of Panama. All these methods, apart (mg/m3) from the Gulf of Panama, recorded from Taylor’s, were implemented in FiSAT II, between 1999 and 2003 (Agujetas 2005), were ver. 1.2.2 (Gayanilo et al. 2005). Pauly’s M tested using the Pearson’s product-moment cor- was multiplied by 0.8 (Pauly 1983) as Green relation coefficient (Sokal & Rohlf 1995). Jacks are a schooling species (Allen & Robert- son 1994). The fishing mortality coefficient F, Green Jack’s fisheries: Values of the was calculated as F=Z-M and the exploitation annual production of Green Jack in Panama ratio as E=F/Z (Sparre & Venema 1998). from 1994-2006 were obtained from Autoridad Marítima de Panamá (Anonymous 1999) and Age structure and maturity: The month- Dirección de Estadística y Censo (Anonymous ly age structure of the stock was estimated 2010a). Catch per unit effort (CPUE) was esti- using Bhattacharya’s method on histograms mated using two different proxies of effort: a) of LS. Average values of LS transformed to the number of boats of the semi-industrial and LT were used to estimate mean age groups artisanal fleets from 1994-2007 (CPUE1), and using NORMSEP. Both methods were also b) the number of boats of the semi-industrial implemented in FiSAT II, ver. 1.2.2 (Gayanilo and artisanal fleets in Panamanian coastal prov- et al. 2005). inces on the Pacific Ocean (i.e. Panamá, Coclé, Green Jacks were sexed by the macroscop- Herrera, Darién, Veraguas y Chiriquí) from ic appearance of their gonads. Monthly, assess- 2000-2004 (CPUE2) (Anonymous 2010b). The ment was made of the ratio males: females scarce data available suggest an increasing and the length of the smallest mature male number of fishing boats per year, between 1994 and female in the samples, MLS. Fully mature and 2007. Missing values within this inter- individuals were recognized by the presence val were approximated using linear regression of gametes, enlarged gonads, and tissue rich models (CPUE1: boats=391·year+776198, R2= in blood vessels. Testes ready to were 0.98, CPUE2: boats=584·year, R2=0.98). whitish and triangular in cross-section and ovi- RMA linear models, such as those in eq.1, ducts were enlarged and full of eggs. were used to describe the association between Cumulative frequency distributions were the annual minima, maxima, and average of the th used to estimate the LS at the 50 percen- Multivariate ENSO/LNSO Index (MEI) and tile (LS50), average standard length at which the CPUE, from December 1994 to December half of males and females in the population 2007. Only results from the models that best were mature. Intervals of 95% confidence of fitted the data were reported. Positive values

LS50 were estimated by randomly sampling of MEI were associated with the occurrence of 2000 times each dataset. Only the largest ENSO events, while negative values with the CI is reported. occurrence of LNSO events (Wolter & Timlin Gonads were weighed to the nearest 0.01g 1993, 1998). CPUE was standardized to stan- using an ACCULAB weighing scale, model dardized values, CPUEs, and to their natural VI-200. The ratio between the gonadic weight logarithms plus a constant 1.5. Bimonthly

(oviducts in females) WG, and WT, times 100, MEI values were aligned to those of CPUEs was used as the gonadic index IG. The size at by matching month 1-month 2 in the former to first massive spawning or at first maturity Lm, month 2 in the latter.

1274 Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 60 (3): 1271-1288, September 2012 RESULTS 60 A Biometrics, growth and mortality: A 50 total of 2 370 male and 2 620 female C. 40 caballus were examined. The smallest fish in the sample measured LS=12.7cm (LT=17.0cm; 30 0.9-1.0 years) and the largest L =45.0cm S 20

(56.5cm; 7.8–8.5 years). The average LS in length (cm) Total 10 males was 28.5±5.2cm (LT 36.4±6.3cm) and in females 28.1±5.3cm (35.8±6.5cm), while 10 20 30 40 50 that of the full sample (±1 standard deviation) Standard length (cm) was LS=28.3±5.3cm (LT =36.1±6.4cm, 2.5- 2000 2.8 years, 495g). The average wet weight of B males was 548±244g (13.4-1 588g) and that of 1500 females was 525±250g (85.0-1 644g). Regression parameters within sexes and 1000 within the pooled sample of both sexes were (g) Weight 500 positive and significant. Models describing the linear associations of LS and LT (Fig. 0 1A) explained a large proportion of the data 10 20 30 40 50 2 variance (R =97%, Table 1). Parameter dif- Standard length (cm) ferences between sexes in models describing 2000 the non-linear associations of LS and WT (Fig. C 1B, Table 1) were significant. However, those 1500 obtained from LT and WT (Fig. 1C, Table 1), were not. 1000

Values of LOPT±10% from eq. 3 were (g) Weight 31.8±3.2cm for males and 32.6±3.3cm for 500 females. Estimates of L ±10% in the pooled OPT 0 data of both sexes were 32.2±3.2cm in the LS 10 20 30 40 50 60 data set, and 38.9±3.9cm in the L data set (Fig. T Total length (cm) 2A,B, Table 2). Values of LOPT from Froese & Binholan (2000) were 29.1cm for males, Fig. 1. Biometric relationships in Green Jacks. (A) 30.8cm for females, 29.8cm for the pooled Standard length vs. total length; (B) Standard length vs. sample of the LS data set, and 37.4cm for the weight; and (C) Total length vs. weight. All regressions are pooled sample of the LT data set. Ranges of significant. Regression parameters summarized in table 1 (all R2 ≥0.94). LOPT of male and female data were similar to that of the pooled sample, so only the latter were considered for further analyses. Accord- ing to the LS data set, 68% of all the fish in the 3. Three independent estimations of L∞ within sample had lengths within the corresponding sex groups were all similar, and 2.6 to 4.0cm optimal ranges, and 6% were mega-spawners larger in females than in males. Similarities

(Fig. 2A). In the LT data set, corresponding were also found between the first two best estimates were 68% and 15% (Fig. 2B). estimates of k, 0.33 to 0.36/year from LS Parameters of the von Bertalanffy mod- data, and 0.32/year from LT data. Differences els, growth performance indexes, and esti- between tO and 0 were almost negligible in the mates of longevity are shown in table 2, while model fitted to values of LS, as they represent- plots of the growth curves are shown in figure ed intervals not larger than 13 days. However,

Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 60 (3): 1271-1288, September 2012 1275 TABLE 1 Parameters describing the relationship between standard and total lengths, and between lengths and weight of Caranx caballus in Pacific Panama

Variables Sex a ± CI (a CI range) b ± CI (b CI range) R2 M 1.57 ± 0.22 1.22 ± 0.01 0.97 L vs. L S T F 1.44 ± 0.23 1.22 ± 0.01 0.97 eq. 1 M + F 1.50 ± 0.15 1.22 ± 0.01 0.97 M 0.11 (0.10 – 0.12) 2.53 (2.51 – 2.56) - L vs. W S T F 0.054 (0.077 - 0.089) 2.57 (2.59 - 2.63) - eq. 2 M + F 0.095 (0.089 – 0.098) 2.57 (2.56 – 2.58) - M 0.027 (0.023 – 0.029) 2.75 (2.73 - 2.78) - L vs. W T T F 0.023 (0.021 - 0.024) 2.78 (2.77 - 2.81) - eq. 2 M + F 0.025 (0.023 – 0.026) 2.77 (2.76 – 2.78) -

M= males, F= females, CI= intervals of 95% confidence, R2= coefficient of determination.

differences between tO and 0 were as high as sex groups within the LS data set (2.89-2.92/ 23.3 days in the model fitted to values of LT. year) and slightly smaller than the performance Corresponding estimates of LO were 0.55 to index obtained from the LT data set (3.05/year). 1.22cm (Table 2). Estimates of longevity were also very similar The growth performance index, a linear between data sets and sex groups, and ranged function of the logarithmic transformations between 8.3-9.4 years (Table 2).

of L∞ and k (eq. 5), was similar between all Estimates of Z from length-converted catch curves were 2.0-1.9/year in LS and LT data sets, respectively. Those obtained from L L 600 m OPT the Jones and van Zalinge’s method (1981), 2.0 and 1.8/year, closely matched them. However, 500 A the Hoenig’s method (1982, Hoenig & Law- 400 ing 1982) produced values of Z equal to 1.0 300 Inmature Mega-spawners and 1.1/year, respectively, as low as half the previous estimates. Those from the Beverton

Frequency 200 & Holt’s (1956), and Ault & Erhardt’s methods 100 (1991, Erhardt & Ault 1992) were between 0 10 20 30 40 50 60 Standard length (cm)

L L 600 m OPT Fig. 2. Size frequency distributions of Green Jacks. Size 500 B interval of optimum length, LOPT ± 10 %, shadowed in 400 grey. Mega-spawners are larger than LOPT + 10 %. Length of immature fish less than Lm (vertical dashed line). Sizes at 300 Inmature Mega-spawners which half the population is mature, LS50 and LT50 are also

Frequency shown (vertical black line). All distributions from pooled 200 samples of both sexes; (A) LS frequency distribution. LOPT 100 = 32.2±3.2cm, mega-spawners are larger than 35.4cm, and immature individuals are smaller than L = 26.5cm; (B) L 0 m T frequency distribution. L = 38.9±3.9cm, mega-spawners 10 20 30 40 50 60 OPT are larger than 42.8cm, and immature individuals are

Total length (cm) smaller than Lm = 33.0cm.

1276 Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 60 (3): 1271-1288, September 2012 = 0.5, and according 0.5, and = et al ., 1993 M et al .,2006ª, 2007 Source (Colima) (Colima) This study = growth performance index, index, performance growth f ’ = Espino-Barr, 2000 Espino-Barr, (Colima 1982 - 1997) (Colima (Las Perlas 2005 - 2006) Cruz-Romero = 0cm, = 0 Gallardo-Cabello L 0.95 9.1 8.3 8.6 9.4 9.0 t 13.4 ± 8.7 8.50 ± 0.42 (cm), according to eq. 3 (above), using average using 3 (above), eq. to according (cm),

f ’ OPT 2.92 2.89 2.90 3.05 2.96 L 2.85 ± 0.33 3.01 ± 0.02 obtained using the Powell-Wetherall’s method, and that of k using and that method, using the Powell-Wetherall’s obtained ∞ and k are the best two estimates of the surface response method and k are the best two estimates O t ∞ = 0.6 (Pauly’s method at 27.5ºC) but in Espino-Barr (2000) 27.5ºC) but in Espino-Barr at method using M = 0.6 (Pauly’s estimated from Colima 0.0 TABLE 2 TABLE = 0.55 = 1.22 -0.03 = -0.52 = -1.00 = -0.74 0.033 0.010 0.064 O O O O O 3.7 days OPT 12.2 days 23.3 days L L 0.02 ± 0.1 L L L -0.05 ± 0.05 (years) = age at which Green Jacks attain the initial size, initial the Jacks attain Green which at age = (years) O t m L 26.5 26.5 26.8 26.5 28.8 29.8 29.9 33.0 32.6 data, G I ), curvature of the growth function; of the ), curvature -1 OPT 28.8 30.8 28.6 29.8 28.2 29.1 32.4 32.3 37.3 33.6 34.2 33.8 36.4 37.4 L k (year k 0.33 0.37 0.33 0.42 0.36 0.34 = age at maturity from maturity at age = m from Colima estimated for this study. L for this study. estimated from Colima 0.35 0.37 0.37 0.42 0.27 ± 0.1 0.35 ±0.01 0 0.32 0.28 0.33 , and L m L ∞ , L 49.1 47.6 46.5 51.5 59.2 62.0 59.0 (cm) = asymptotic length, = asymptotic (cm) ∞ OPT 47.5 49.5 47.9 45.0 46.0 45.0 L 53.5 ± 6.5 53.7 ± 2.4 the scan method in FISAT II. Middle and bottom values of L II. Middle and bottom the scan method in FISAT Parameters of the von Bertalanffy models. Within sex groups, top value of L Within models. of the von Bertalanffy Parameters F M Sex M + F M + F M + F M + F M + F M = 0.35. S S T T T = longevity (years). L = longevity L L L L L

Data set 0.95 to Froese and Binohlan (2000) (below), L Binohlan and Froese to where = females, F males, M = t

Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 60 (3): 1271-1288, September 2012 1277 70 groups from the Green Jack sample (A through This study: L H, in LS) (Table 4). Groups A - E were also T found by NORMSEP (in L ), but NORMSEP 60 Gallardo-Cabello et al. (2007): L T T pooled Bhattacahrya’s F and G into a single Cruz-Romero et al. (1993): L T group, and was unable to discriminate group 50 H. Chronological ages in groups A through E in both analyses were different by no more than 40 2.5 months (i.e. maximum difference found in Group E) (Table 4). This study: L S Male to female ratios ranged from 1:1.64 30 Length (cm) Length Espino-Barr (2000): L S in July to 1:0.77 in May, averaging 1:1.28±0.98 per month during the sampling period. The sex 20 ratio of the full sample was 1:1.1. The smallest

mature male found was MLS=18.5cm long (1.4 10 years, 146g) and the smallest mature female

MLS=16.8cm (1.2 years, 111g). The average 0 standard lengths at which half of the popula- 0 2 4 6 8 10 tion was mature in males and females were Time (years) very similar, LS50=30.5±0.1cm (LT50=38.8cm, 2.9-3.2 years) and LS50=30.2±0.1cm (38.7cm, Fig. 3. Von Bertalanffy growth models fitted to data sets 2.8-3.2 years) respectively (Fig. 4A,B). of L (white circles) and L (black circles). Parameters S T The distribution of I maxima in relation summarized in table 2. G to LS was similar in both sexes. Low values of IG maxima (1 or 2) were common among fish as large as LS=26cm. IG maxima increased abruptly, up to values of 9 and 10 in males and

0.1-0.2 units off from Hoenig’s (1982, Hoenig females attaining LS=Lm=26.5cm and larger, & Lawing 1982) estimates (Table 3). and LT=Lm=33.0cm and larger (2.3–2.5 years). The Rikhter & Efanov’s (1976) method In fish larger than LS=32.0cm (LT=43.0cm), I maxima decreased gradually to four in produced estimates of M=0.7/year in the LS G fish of L =41cm (L =50.0cm) and larger (Fig. data set (Lm=26.5cm; 2.3 years) and M = 0.6/ S T 4C,D). The age at first maturity of the pooled year in the LT data set (33cm, 2.5 years). Tay- lor’s (1958, 1960) estimates of M were 0.3/year sample was Lm=26.8cm in the LS data set in all data sets, and Pauly’s (1980, 1983, 1984) (20.0-35.9cm), and Lm=32.6cm in the LT data were 0.6/year (at 27.4°C) (Table 3). set (24.3-43.7cm). Of all the fish in the sample, 10-13% were immature or smaller than the In the LS data set, estimates of F obtained from the catch curve mortality ranged between estimates of Lm (Fig. 4C,D). 1.3-1.7/year, while those from Hoening’s The reproduction of Green Jacks is associ- method (1982, Hoenig & Lawing 1982) ated with the upwelling events that annually ranged between 0.5-0.8/year. These values of occur in the Gulf of Panama. Monthly SST

F were similar to those in the LT data set, averages were inversely correlated to monthly as they ranged from 1.3-1.6/year and from IG maxima (Pearson’s r=-0.67, p≤0.018 males; 0.4-0.7/year,-respectively. High values of F -0.80, p≤0.002 females) and to proportions matched high values of E and ranged between of mature individuals (0.74, p≤0.006 males; 0.4-0.8 (Table 3). -0.72, p≤0.009 females). Monthly chlorophyll surface concentrations were directly correlated

Age structure and maturity: Bhattacha- to IG maxima (0.77, p≤0.001 males; 0.918, rya’s method suggests the presence of eight age p≤0.003 females) and to the proportion of

1278 Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 60 (3): 1271-1288, September 2012 T = average Source This study Espino-Barr, 2000 Espino-Barr, (Colima 1982 - 1997) (Colima alues under Z are estimates (Las Perlas, 2005 – 2006) V estimated using Rikhter and Rikhter using estimated M E 0.5 0.7 0.4 0.7 0.8 0.7 0.8 0.7 0.7 0.5 0.7 – 0.9 0.8 ± 0.1 0.7 – 0.9 0.8 ± 0.1 F 0.5 1.3 0.4 1.3 1.7 0.8 1.6 1.4 0.7 0. 5 = age in years at which half of the population is mature, ) = age in years at which half of the population m 1.6 – 1.9 1.8 ± 0.2 0.5 – 4.7 1.9 ± 0.1 M 0.7 0.6 0.6 0.7 0.3 0.3 0.3 0.6 0.3 0.6 longevity (years), t(L longevity TABLE 3 TABLE 0.3 – 0.6 0.4 ± 0.1 0.2 – 0.4 0.3 ± 0.1 0.9 = Mortality rates in Green Jacks Mortality = 0.03 = 0.03 = 0.06 = 0.06 0 0 0 0 = -0.05 – 0.09 0 alues of Z show intervals of 95% confidence. Other values show standard deviations. of 95% confidence. alues of Z show intervals ) = 2.3 ) = 2.5 ) = 2.5 ) = 2.3 V m m m m T = 27.4 ° T = 27.4 ° = 8.6 t = 8.6 t = 9.4 t = 9.4 t t(L t(L t(L t(L Parameters 0.95 0.95 0.95 0.95 T = 26.0 ° – 29.0 t t t t = 7.7 – 20 t 0.95 t P P P TA TA TA TA TA RE RE RE RE alues of Pauly´s 0.8 M, F, and E from Mexico were estimated from data published by Espino-Barr (2000). from data and E from Mexico were estimated alues of Pauly´s 0.8 M, F, ), and Pauly’s ( P ) 0.8 M. Other symbols are: t ), and Pauly’s V ± 0.2 ± 0.1 ± 1.3 ± 0.2 ± 0.2 2.0 1.8 1.3 1.3 0.95 0.94 0.6 - 5.0 2.0 1.9 2.2 1.1 1.0 Z H H CC CC CC AE AE BH BH JvZ JvZ S T T L L L Data set SST (Celsius), F = Z- M, E / Z. SST , from length-converted catch curves ( CC ) . catch Z , from length-converted mortality, Total ), all in separate rows. Natural mortality rows. Natural separate in all ( BH ), method Holt’s and Beverton and ( H ), method Hoenig’s ( JvZ ), method Zalinge’s van Jones and from method ( TA Taylor’s ( RE ), Efanov’s

Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 60 (3): 1271-1288, September 2012 1279 TABLE 4 Age distributions and structure of Green Jacks from Las Perlas Archipelago, following Bhattacharya’s and NORMSEP methods

Bhattacharya Expected values of L NORMSEP Group Age T Age Age group mean LS from LS Age group mean LT A 23.0 ± 0.60 1.9 29.6 28.3 ± 0.64 2.1 2.0 B 26.6 ± 0.83 2.3 34.0 31.4 ± 0.41 2.4 2.3 C 29.1 ± 0.13 2.7 37.0 34.9 ± 0.88 2.8 2.7 D 31.2 ± 0.44 3.0 39.6 38.5 ± 0.91 3.3 3.2 E 33.9 ± 0.62 3.5 42.9 43.3 ± 1.50 4.2 3.9 F 37.1 ± 0.10 4.2 46.8 47.7 ± 0.59 5.2 4.9 G 38.1 ± 0.02 4.5 48.1 H 40.4 ± 0.00 5.2 50.9 - -

LT obtained from LS using eq. 1, shown as mean ± standard deviation (cm). NORMSEP age group means are from averaged sets of NORMSEP results with their corresponding standard deviations. Age is given in years.

1.0 A B

LS50 = 30.2 - 30.5 cm L 50 = 38.7 - 38.8 cm 0.5 T Cumulative Frequency Cumulative 0.0

12 C 10 D 8 I G 6 Lm = 26.5 cm Lm = 33.0 cm 4 2 0 10 20 30 40 50 10 20 30 40 50 60 Standard Length (cm) Total Length (cm)

Fig. 4. Size at which half of the population is mature and length at onset of maturity; (A) Cumulative frequency distribution of LS. Vertical lines at LS50 = 30.2±0.1cm in males and 30.5±0.1cm in females; (B) Distribution of IG values in relation to LS. After Lm = 26.5cm (vertical line), individuals matured massively; (C) Cumulative frequency distribution of LT. Vertical line at LT50 =38.7±0.1cm in males and 38.8±0.1cm in females; (D) Distribution of IG values in relation to LT. After Lm =33.0cm (vertical line), individuals matured massively. Black circles are males and white circles females.

1280 Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 60 (3): 1271-1288, September 2012 mature individuals (0.91, p≤0.001 males; 0.88, occurred in December 2005 (0.98 males: 0.88 p≤0.001 females). The largest values of IG females) and April 2006 (0.42:0.36) and other and mature individuals occurred approximate- high values (>0.30) occurred also in January ly three months before the local upwelling and February. Mature individuals (1-25% of the reached its maximum, a time when the low- current sample) were found every month, and est values of SST and the highest concentra- the monthly proportion of mature males and tions of chlorophyll occurred (Fig. 5A,B,C). females was approximately constant during the

IG maxima and the proportion of mature indi- sampling period (Fig. 5C). viduals changed synchronously in relation to environmental variables (Fig. 5A,B,C). Male Green Jack’s fisheries: The CPUE of and female annual values in IG maxima peaked Green Jacks was significantly associated to in December for males (10.5), in January MEI. Standardized values of CPUE1s and for females (10.6), in April (6.9 males: 5.4 their natural logarithms were best described females), and in September (5.0 males: 4.3 by the minimum annual values of MEI (CPU- 2 females). Notable values of IG maxima (>0.25) E1s=[1.17±0.85] + MEI ∙ [2.34±1.16], R =0.54; also occurred in January, February, August, Ln[ CPUE1s + 1.5] = [1.02±0.28] + MEI ∙ and October (Fig. 5B). The highest propor- [1.65±0.62], R2=0.54) (Fig. 5D,E,F). Models tion of individuals with fully mature gonads using MEI minimum annual values to predict

SST & Chlorophyll MEI Minima 4 1 A D 2 0 0 -1 -2 -4 -2

IG Maxima CPUE1s 12 4 B E 8 2

4 0

0 -2 % Mature Individuals L (CPUE1s + 1.5) 1.0 2 n C 1 F 0.5 0 -1 0 -2 JN JL AG SP OP NO DC JA FE MA AP MY 94 95 96 97 98 99 00 01 02 03 04 05 06 07

Months Years

Fig. 5. Environmental and biological variables; (A) Standardized average SST (°C, thin line) and chlorophyll concentrations 3 (mg/m , thick line) in the Gulf of Panama between 1999 and 2003. Error bars are standard deviations; (B) IG maxima between June 2005 and April 2006. Black circles are males and white circles females; (C) Proportion of mature individuals between June 2005 and April 2006. Black circles are males and white circles females. Regression parameters summarized in table 1; (D) MEI yearly minimum values; (E) CPUE1s, standardized catch per unit effort estimated using the size of the semi-industrial and artisanal fleet from 1994 to 2007; (F) Log-transformed values of CPUE1s. Regression parameters summarized in table 1.

Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 60 (3): 1271-1288, September 2012 1281 CPUE2s and those using MEI annual averages of Green Jacks from Las Perlas recorded in this to predict CPUE1s, explained poorly the vari- study, LS=28.3±5.3cm (LT=36.1±6.4). ability of the data sets (R2<0.31). Old fish play a very important role in the long-term survival of populations, as they are reservoirs of desirable genes and a safeguard DISCUSSION to recruitment failure. They are more fecund Within its range of distribution, the Green than younger individuals, produce larger eggs Jack is one of the most abundant pelagic fish with better chances of survival, and their pres- of commercial interest in the Central Eastern ence is a measure of the population’s resilience Pacific. From 1994-2002, its yearly average (Froese 2004). The largest Green Jacks from production in Panama ranged between 159- Las Perlas measured LS=45.0cm (LT=56.0cm, 850t/year (446±216t/year) and based on the 8.2-7.8 years, 1 644g) and were also larger than those from Colima, L =44.0cm (L =53cm, available underestimated local fishing statis- S T 1 689g) (Espino-Barr 2000), but both were tics. Despite the sudden reduction of catches smaller than the record sizes attributed to in 1994-95 (850-341t), in 1998-99 (469-159t), the species; 70cm total length (Robertson & and in 2003-04 (1 436-737t), Panama increased Allen 2008) and 55.0cm fork length (Froese its yearly production 3.4 times in 2006-08 & Pauly 2010). Stocks with a percentage of (477-1 640t), boosting its average production mega-spawners lower than 20% are very sus- to 1 234±656t/year during the same period ceptible to the effects of random events and (Anonymous 1999, 2010a). massive recruitment failures (Froese 2004). The Las Perlas Archipelago was the most Only 6-15% of Green Jacks in Las Perlas important fishing ground of Green Jacks until sample were mega-spawners. 2007. By the time Law Nº18 was approved by The smallest Green Jacks from Las Per- the Assembly of Panama in May of that year, las, measuring LS=12.7cm (LT=17.0cm, 0.9-1.0 semi-industrial fisheries operating in the Archi- years, 50g), were smaller than the smallest pelago were responsible for approximately from Colima collected between 1982-1998 70% of the catches. (L =14cm, L =19cm) (Espino-Barr 2000). Even although the production of Green S T Fish measuring between 16.8-18.5cm (MLS) Jack in the state of Colima, Pacific Mexico, were the youngest mature Green Jacks from is of one order of magnitude smaller than that the archipelago, but most individuals matured of Panama it has been monitored since the simultaneously and massively after attaining 1980’s (Cruz-Romero et al. 1993, Espino-Barr Lm=26.5cm (in LS data set) and Lm=33.0cm (in 2000, Godínez-Domínguez et al. 2000, Navar- the LT data set) (2.3-2.5 years). All estimates of ro-Rodríguez 2000, Rojo-Vázquez et al. 2001, Lm from Las Perlas were also similar to those Gallardo-Cabello et al. 2006a, b, 2007). From from Colima. Typically, Lm is lower than the 1980-2002, Green Jack catches ranged between size at which half of the population is mature 9-250t/year (93t on average) and in 2007 they or LS50, and lower than LOPT ± 10%. In Las represented 6% of all the production in this Perlas samples, 10-13% of all fish were smaller Mexican state, only surpassed by that of the than Lm meaning that between 2005 and 2006, highly profitable snappers (Lutjanidae) (Gal- one in every 10 Green Jacks caught in fisher- lardo-Cabello et al. 2007). The average body ies from Las Perlas never had a chance to length of Green Jacks from Colima, LS=23.0cm reproduce. (LT=29cm), and their L∞ (47.0-68.0cm) (esti- Gallardo-Cabello et al. (2007) also esti- mated using LS), did not show any significant mated parameters for the power law relation- trend between 1982-1997 (Espino-Barr 2000). ship between LT and WT of Green Jacks from The average length remained slightly smaller Colima, a=0.012 and b=2.972 (N=747). In during this period of time than the average LS samples from Las Perlas, parameters a=0.025

1282 Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 60 (3): 1271-1288, September 2012 and b=2.77, were highly significant (p<0) and Las Perlas, the first best estimate of k obtained, significantly different from those reported in from the surface of response method from the

Gallardo-Cabello et al. (2007). Other authors, LT data set, was as low as 0.28/year. The second studying the length-weight relationship of best estimate, 0.33/year, was closer to the value Green Jacks, used weights from eviscerated of k obtained from the Powell-Wetherall’s fish (Gallardo-Cabello et al. 2006a, 2007) or method (Powell, 1979; Wetherall, 1986), 0.32/ used fork lengths as independent variables year. If the growth signal in the data set is (e.g. Froese & Pauly 2010), making further robust, approximation methods are expected comparisons difficult with our current results. to produce congruent parameter values for Significant differences in equation parameters the same data sets. In contrast, if the growth between sexes in non-linear models of LS signal is poor, several different combinations and WT indicated that the body weight of of parameter values may explain equally well males increased faster per unit length than the same data set. The lack of growth signal that of females. All parameter estimations is probably responsible for growth parameters were well within the range of those reported from the Espino-Barr (2000) study to be so in other species of the family Carangidae variable, as she had access to only 1 320 Green (Froese & Pauly 2010). Jacks to describe the 16-year long behavior of Average sex ratios and maximum values fisheries in Colima (on average, only 83 fish/ of LS, LT, L∞, k, and longevity, in samples from year). Las Perlas, indicate that Green Jack females In samples from Las Perlas, Z ranged were somewhat more numerous and perhaps between 0.9-2.0/year. Estimates from the longer living than males. Females also grew length-converted catch curves and from the slightly faster and larger than the opposite sex. Jones and van Zalinge’s (1981) method, were However, all these differences were very small, similar, as expected, as both use comparable and in general, males and females were indistin- assumptions (Pauly 1984). All mortality rates guishable from their external morphology. For from Las Perlas were high, but they were still these reasons, only growth models fitted to the lower than the 16-year long average of Z, 2.2 pooled data were used for further comparisons. ±1.31 year-1, estimated from yearly catch curve All growth curves of Green Jacks from values from Colima. Colima plotted within those of models fitted Instantaneous mortality rates from Hoe- to the LS and the LT data sets from Las Perlas. nig’s (1982; Hoenig & Lawing 1982), Bever- Most values of k were very similar between ton and Holt’s (1956), and Ault and Erhardt’s data sets, localities, and sources, ranging from (1991; Erhardt & Ault 1992) methods produced

0.32-0.35/year. In contrast, L∞ estimates were estimates that were approximately one-half of all dissimilar, starting at 59.2cm (LT data set) in those obtained from length-converted catch Las Perlas, 55.4-51.5cm in Colima, and finish- curves and from the Jones and van Zalinge’s ing at 47.6cm in Las Perlas (LS data set). Simi- (1981) method. Both types were expected to lar values of L∞ in samples from Las Perlas and differ, as estimates from the first three models Colima suggest comparable environmental and are based on longevity, asymptotic length, biological conditions for this species in both mean length, and k, while those from the localities, while similar values of k, equivalent remaining models depend on the distribution life history traits. Values of k >0.3 are com- of catches, expressed as lengths or counts, and monly associated with highly productive stocks ordered according to a proxy of age (Sparre & (e.g. Dulvy et al. 2004). Venema 1998). As length parameters are used However, not only were the range of val- in a number of these models, estimates of Z are ues of L∞ and f’ (2.62-3.08) the largest found obviously strongly (and inversely) correlated in this study, but also those of longevity (7.7-20 with them, as shown by McGurk (1986) and years) and k (0.15-0.39/year). In samples from the current results. For example, in Green Jacks

Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 60 (3): 1271-1288, September 2012 1283 from Las Perlas Z=1.9/year and L∞=59.2cm, 0.9-1.0 year old (LS=12.7cm, LT=16.5cm). The while in those from Colima; Z=2.2/year and bias against small sizes in Las Perlas samples

L∞=51.5-55.4cm. In Caranx caninus, values (

2.02/year), Megalaspis (0.39-1.36/year), Selar- tive events. However, the IG index indicates ioides (1.46/year), Seriola (0.50-0.94/year), that there are at least three reproductive events and (0.49-1.36/year). every year: in August-September, December- Values of E ranging from 0.4-0.8/year February, and April. Under both scenarios, the in Green Jacks from Las Perlas, and 0.8/ evidence points to December as the strongest year in fish from Colima, suggest that high reproductive month. Information that could exploitation rates occur in both localities. help corroborate these patterns, such as recruit- Subtle evidence of the high intensity of fish- ment and temporal distribution of larvae in Las ing in Colima is observed in the low values Perlas, is not available. of L∞ and LOPT and the high values of k of its Two to three months was the delay samples, compared to those from Las Perlas, between the yearly maximum of IG and the while M (from Pauly’s equation) remains top percentage of fully mature individuals comparable in both localities (but not accord- in the samples (occurring in December), and ing to Espino-Barr 2000). the highest chlorophyll concentration and the Six separate age groups were found by lowest SST. Spawning two to three months in NORMSEP, clearly representing individuals advance of the moment of highest productiv- between 2-5 years old. Green Jacks recruit to ity guarantees a continuous food supply to the the population in Las Perlas before they reach growing larvae. The growth models presented

1284 Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 60 (3): 1271-1288, September 2012 here suggest that approximately 1.5 months are b, Guzman et al. 2008). However, the results required for Green Jack larvae to reach 2.4cm demonstrate that 10-13% of the current cap- of total length, the size of the largest juveniles tures of Green Jacks are on average immature sampled in the Central Eastern Pacific by Sum- individuals, 68% of catches are within the LOPT ida et al. (1985). To achieve this size, larvae range, and only 6-15% of fish in the popula- must grow 0.5mm/day, a rate well within the tion are mega-spawners. According to Froese range reported in other carangids, 0.2-0.8mm/ (2004), this is enough evidence to assert that day (Leis et al. 2006). This result suggests Green Jacks from Las Perlas are overfished. At that abundant food may be available in Las the same time, results also describe a popula- Perlas for Green Jacks larvae, hatched between tion with fast growing individuals, with rates November and February, to become juveniles of natural mortality similar to those of other two months later. carangid species, and under strong fishing The abundance of Green Jacks in the pressure. It is speculated that the production region increases during the warmest years, of Green Jacks in Las Perlas is probably main- especially in those in which ENSO occurs tained by the enormous availability of larvae (Espino-Barr 2000, Godínez-Domínguez et al. 2000, Rojo-Vázquez et al. 2001). Espino- resulting from two or three reproductive events Barr (2000) measured the cross-correlation each year, fueled by one strong annual upwell- between the Multivariate ENSO Index (MEI) ing that boosts the primary productivity of the and the monthly catch per unit effort (CPUE) region, and by the capacity of these larvae to of Green Jacks from Colima, in a 16-year long successfully recruit to the local population. time series with 192 data points (one for each Under this scenario, if recruitment fails due to month). The best correlation between these an unfortunate combination of environmental two time series (r=0.412) was obtained when and man-made conditions, and the fisheries both data sets were shifted by 16 months. No of Green Jacks collapse, the low proportion clear explanation was given for such a dif- of mega-spawners will hamper their recovery. ference. Las Perlas time series had only 14 Implementing strategies to increase the propor- data points, one for each month, the reason tion of mega-spawners in an exploited popula- why the temporal structure of Las Perlas data tion is not a simple task in fisheries where the was dismissed. However, a significant direct upper limits of size are usually not regulated, association between the CPUEs and the cor- and larger fish are targeted from the very onset responding yearly minimum values of MEI of the fishing activities. was found. Given the time scale of the current analysis, shifting MEI values in relation to the CPUEs time series did not improved the fitting ACKNOWLEDGMENTS scores. The results suggest that the minimum The authors thank Carlos Guevara and values of MEI could be used as an additional tool to evaluate a posteriori and very roughly, Carlos Vega for processing samples and Julio the productivity of Green Jacks during a given Agujetas for providing access to satellite data year, by comparing current and previous annual and all fishermen who provided information records with the oceanographic conditions of about the fisheries in Las Perlas. The Govern- the region. ment of Panama provided permits to work in It is also apparent that the current status the area. This research was partially sponsored of Green Jacks is far better than that of other by DEFRA’s Darwin Initiative Fund (UK), marine commercial resources in Las Perlas, Heriot-Watt University, Smithsonian Tropical such as the severely overexploited pearl oys- Research Institute, Panama, and Universidad ters, lobsters, and conchs (Cipriani et al. 2008a, Simon Bolivar (GID-67), Caracas, Venezuela.

Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 60 (3): 1271-1288, September 2012 1285 RESUMEN Estadística y Censo. (Downloaded: November 1, 2010, http://www.contraloria.gob.pa/dec/). El jurel verde o “cojinúa”, Caranx caballus, se dis- tribuye a lo largo de la costa del Pacífico Oriental. En el Anonymous. 2010b. Publicacions: Estadísticas Ambien- Archipiélago de Las Perlas, Panamá, la cojinúa fue pescada tales 1998-2000 and Estadísticas Ambientales sin control para sostener mercados locales hasta el 2007, 2002-2004. Contraloría General de la República de fecha en la que esta región fue declarada área marina pro- Panamá. Dirección de Estadística y Censo. (Down- tegida. En este primer estudio para Panamá, se analizaron loaded: November 1, 2010, http://www.contraloria. desde junio de 2005 a junio de 2006, 4 990 individuos en gob.pa/dec/). las descargas del Mercado Central de Mariscos provenien- tes de Las Perlas. La longitud media total de esta especie Ault, J.S. & N.M. Ehrhardt. 1991. Correction to the Bever- fue de 36.1±6.4cm y la longitud óptima, 38.9cm. Aproxi- ton and Holt Z-estimator for truncated catch length- madamente, 68% de los individuos muestreados poseen frequency distributions. ICLARM Fishbyte 9: 37-39. longitudes dentro de ±10% de la longitud óptima, pero sólo seis (15%) eran mega-reproductores. Los parámetros de la Beddington, J.R. & J.G. Cooke. 1983. On the potential ecuación de von Bertalanffy describen la especie como de yield of fish stocks. FAO Fish. Tech. Pap. 242, Rome, larga vida y de rápido crecimiento, mientras que las tasas Italia. de mortalidad indican que la cojinúa está bajo una alta presión de pesca. La longitud estándar a la que la mitad de Bernal-Ornelas, I.H., M. Saucedo-Lozano, E. Espino-Barr, la población es sexualmente madura es 38.8cm y el tamaño A. García-Boa, E.G. Cabral-Solis & M. Puente- de maduración masiva, 33cm. Sólo entre el 10-13% de -Gómez. 2005. Análisis de la alimentación de Caranx los individuos muestreados son inmaduros. La cojinúa se caballus Günther 1868, en la costa de Manzanillo, reproduce 2-3 veces al año, con picos en diciembre, abril y Colima, México. Abs. Mem. XVIII Cong. Nac. Zool., probablemente septiembre, y recluta a la población por lo Monterrey, Mexico. menos dos veces al año. Los valores mínimos anuales del Índice ENSO/LNSO multivariado (MEI) son los mejores Beverton, R.J.H. & S.J. Holt. 1956. A review of methods predictores de la CPUE de esta especie (R2=0.54). Nues- for estimating mortality rates in exploited fish popu- tros resultados demuestran que la cojinúa en el Pacífico lations, with special reference to sources of bias in Panameño está sobreexplotada por lo que recomendamos catch sampling. Rapp.P.-V.Réun. CIEM, 140: 67-83. elevar la talla mínima de captura para permitir que aumente la proporción de mega-reproductores en la población con el Cipriani, R., H.M. Guzman & M. Lopez. 2008a. Harvest fin de garantizar la sostenibilidad del recurso. history and current densities of the pearl oyster Pinc- tada mazatlanica (Bivalvia: Pteriidae) in Las Perlas Palabras clave: Caranx caballus, cojinua, jurel verde, and Coiba Archipelagos, Panama. J. Shellfish Res. evaluación pesquera, Pacífico oriental, Panamá. 27: 691-700.

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