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. 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. 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. Finray ageing proved relatively precise (coefficient of variation [CV] = 4.24%), although less so than otolith ageing (CV = 1.45%). Finray ages agreed with otolith ages the majority of the time (CV = 3.15% and concordance correlation coefficient = 0.991) for E. itajara from 0 to 18 yr of age. Based on a test of symmetry, finray ageing was also relatively unbiased for fish 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. 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. Finray ageing could significantly reduce the need to sacrifice protected E. itajara to assess their population recovery. KEY WORDS: Epinephelus itajara · Goliath grouper · Otoliths · Finrays · Non-lethal ageing · Florida Resale or republication not permitted without written consent of the publisher OPEN PEN ACCESS CCESS Contribution to the Theme Section 'Range-wide status and conservation of the goliath grouper'Endang Species Res 7: 213-220, 2009 their original distribution range throughout southwest Florida and the Florida Keys, while the frequency of adult sightings has increased in offshore artificial structures of southwestern Florida (Cass-Calay & Schmidt 2003, Porch & Eklund 2003, Frias-Torres 2006, NMFS 2006. This apparent population increase has generated requests by fishermen to re-open the fishery in Florida.Assessing the population status of both juvenile and adult goliath grouper is critical for addressing these over-exploitation and recovery issues (Kingsley 2004). Obtaining biological data is essential for estimating population parameters (i.e. growth, age-specific reproductive potential, recruitment, and mortality rates; Haddon 2001) that are used as input to stock assessments to predict recovery trajectories. The problem faced by management agencies is how best to obtain the data required for stock assessment without jeopardizing the very population they are trying to protect. The crux of the problem is that most bony fishes are aged by using their sagittal otoliths, which requires killing the fish. Ageing goliath grouper with this method is clearly inconsistent with the goal of conserving the species. Non-lethal ageing methods present a viable alternative, in which dorsal or pectoral finrays can be removed from live fish, which are subsequently re...

While juvenile Atlantic goliath grouper, Epinephelus itajara (Lichtenstein, 1822), are known to depend on mangrove root structure, relationships with water properties (e.g., salinity) and depth remain unclear or understudied. Because availability of suitable mangrove habitat has been suggested as the primary bottleneck to the recovery of this threatened species in the US, we investigated habitat associations of juvenile Atlantic goliath grouper with respect to physical water properties within mangrove habitats. Our study was conducted in six coastal rivers and three canals within the Ten Thousand Islands region of southwest Florida. Results suggested that juvenile Atlantic goliath grouper differed in how they associated with specific mangrove habitats based on season and size. We found that smaller juveniles (<340 mm TL) appeared to have stronger associations to physical water characteristics than larger (≥340 mm TL) juveniles. Both large and small juveniles showed the strongest associations with DO (i.e., >3 mg L −1 ) within mangrove habitat. For small juveniles, extreme temperatures influenced habitat association; for large juveniles, extreme salinity influenced distribution. We also found evidence that juvenile Atlantic goliath grouper associated more with natural rivers over man-made canals. The present study has utility for delineating suitable mangrove habitats for protection and potentially in the design of sampling surveys that aim to estimate population abundance.

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Previous studies have developed size-at-age curves for goliath grouper; however, these data were based on relatively few immature individuals, and age estimation was otolith-based, requiring sacrifice of this federally protected fish. In the present study, scales, dorsal fin-rays and dorsal spines were explored as potential non-lethal ageing alternatives for juvenile goliath grouper. Annulus marks were validated using marked-recaptured fish, oxytetracycline injections, and edge analysis. A subset of fish was sacrificed to compare the scale, spine and ray ages to otolith ages. A 40% recapture rate provided a useful time series of in situ age and growth data. Scale and ray ages were unreliable, but dorsal spines demonstrated agreement with corresponding otolith ages. Annuli were best represented by translucent bands in spines, as opposed to opaque bands in otoliths. Spines were positively validated for periodicity of annulus formation. Annuli formed at different times of the year in spines than in otoliths. By correcting for this difference using a biological age method, better agreement between otolith and spine age was achieved. Dorsal spines are recommended as the primary method for ageing goliath grouper between the ages of 0 and 6 yr. This study illustrates the use of a non-lethal method to determine age of a protected species.