From August 1996 to March 2000, fish were sampled (n=3.539) in the northeast portion of the Brazilian Exclusive Economic Zone. The age and growth of Lutjanus jocu was assessed through readings of growth marks in sagitta otoliths.
The growth of larvae captured in plankton tows in July and September 2004 was substantially faster than that of larvae sampled in May, which coincided with warmer sea surface temperatures, highlighting a potentially important relationship relating temperature (and therefore geography) and settlement success These results provide further evidence for the importance of protection and restoration efforts for estuaries and bays along this well-developed coastline. The data also suggest that spotfin croakers segregate themselves sexually during the spawning season, when recreational fishing from jetties will target males and fish caught in bays and estuaries are more likely to be spawning females. Catches in rocky-reef areas were limited but tended to increase with water temperature. The juvenile and adult catch per unit effort reflected a clear pattern of habitat selectivity, with fish strongly preferring soft-bottom habitats. Multiple models were used to estimate mean length at age, including models that utilize larvae as well as juveniles and adults, and the model selection results suggest sexual dimorphism in growth patterns. The maximum otolith-based age in the present study was 24 years?14 years greater than in a previous scale-based aging study. Because of uncertainties associated with the estimates of mortality, the option of increasing fishing effort to obtain higher yields could be considered, but reduction of mesh size to meet minimum marketable size (tc=3.5 per year) would be preferable under the prevailing conditions in Kuwait’s fishery.Ībstract Spotfin croakers Roncador stearnsii, a prized recreational catch, were collected throughout the Southern California Bight, primarily as bycatch from a long-term, scientific gill-net collection effort. The current F values were always below F0.1 and maximum Fmax for all M values used in simulations. Higher yield-per-recruit occurred at lower M (0.20) and higher F (>0.80) at tc=3.5–4.0 years however, at the current tc=5.1, marginal increase in yield beyond F=0.50 was small. The effect of different fishing mortality (F, 0.1–1.5), and M (0.20, 0.25, and 0.30), and age at first capture (tc, 1.0–5.5) on yield-per-recruit of nagroor were evaluated. Natural mortality rate (M) was 0.20 per year and total mortality rate (Z) ranged from 0.24 to 0.36 per year. Maximum age recorded was 36 years and the largest fish was 75 cm total length (TL). Significant differences in length-at-age and estimated growth parameters were found between sexes, with females growing larger than males. Estimated parameters of the von Bertalanffy growth function for pooled data were L∞=62.16 cm, K=0.27 per year, and t0=−0.47 year (n=1183). The age, growth and mortality of nagroor, Pomadasys kakaan, were determined from sectioned otoliths of fish from Kuwait waters. itajarato assess their population recovery. Finray ageing could significantly reduce the need to sacrifice protected E. Clearly, the non-lethal finray ageing method can be used as an alternative to using otoliths for goliath grouper at least up to 18 yr of age. Further evaluation of any limitations of the method will depend on obtaining more samples, especially from larger, presumably older, fish. Based on a test of symmetry, finray ageing was also relatively unbiased for fish up to 18 yr of age. Finray ages agreed with otolith ages the majority of the time (CV = 3.15% and concordance correlation coefficient = 0.991) for E. Finray ageing proved relatively precise (coefficient of variation = 4.24%), although less so than otolith ageing (CV = 1.45%). Paired finray and otolith samples (n = 21) were collected opportunistically from fish that had died primarily from red tide or hypothermal events in Florida coastal waters. We evaluated the precision and accuracy of a non-lethal ageing method for goliath grouper Epinephelus itajara, listed as critically endangered on the IUCN Red List of Threatened Species.
Currently, there is a conflict between the need to conserve protected fish species and the need to use lethal methods to collect essential biological data, such as age, to assess their population status and recovery trends.
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