Hare, J.A., Manderson, J.P., Nye, J.A., Alexander, M.A., Auster, P.J., Borggaard, D.L., Capotondi, A.M., Damon-Randall, K.B., Heupel, E., Mateo, I., O'Brien, L., Richardson, D.E., Stock, C.A., and Biege, S.T. 2012. Cusk (Brosme brosme) and climate change: assessing the threat to a candidate marine fish species under the US Endangered Species Act. – ICES Journal of Marine Science, 69: 1753–1768. In the Northwest Atlantic Ocean cusk (Brosme brosme) has declined dramatically, primarily as a result of fishing activities. These declines have led to concern about its status, which has prompted reviews under the US Endangered Species Act and the Canadian Species at Risk Act. Changes in distribution and abundance of a number of marine fish in the Northwest Atlantic have been linked to climate variability and change, suggesting that both fishing and climate may affect the status of cusk. Our goal was to evaluate potential effects of climate change on Northwest Atlantic cusk distribution. Coupling a species niche model with the output from an ensemble of climate models, we projected cusk distribution in the future. Our results indicate cusk habitat in the region will shrink and fragment, which is a result of a spatial mismatch between high complexity seafloor habitat and suitable temperature. The importance of habitat patch connectivity for cusk is poorly understood, so the population-level consequences of climate-related habitat fragmentation are uncertain. More broadly, climate change may reduce appropriate thermal habitat and increase habitat fragmentation for other cold-water species in the region; thereby, increasing the potential for regional overexploitation and extirpation.

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Juvenile French grunt Haemulon flavolineatum and schoolmaster Lutjanus apodus were captured in mangrove and seagrass stations in St. Croix, and Puerto Rico in 2006 and 2007 to determine whether areas for juvenile fish can be discriminated by means of otolith chemistry. Concentrations of 16 elements were determined in 0-group fish otoliths using laser ablation-inductively coupled plasma mass spectrometry. Two stable isotopes, δ 18 O and δ 13 C, in French grunt and schoolmaster otoliths were also analyzed. Multi-elemental signatures for both species differed significantly (p < 0.001) among mangrove and seagrass stations within both islands. Furthermore, concentrations of 6 elements (Sr, Ba, Cu, Mg, Co, Na) as well as δ 18 O and δ 13 C for both species within each year differed significantly among mangrove and seagrass stations within islands (p < 0.001). Classification success for French grunt and schoolmaster juvenile areas within St. Croix across years ranged from 87 to 92% and from 76 to 77%, respectively, whereas in Puerto Rico, classification success for French grunt and schoolmaster for the 2 years ranged from 80 to 84% and 84 to 87%, respectively. Classification success between mangrove and seagrass habitats (stations combined) in Puerto Rico for French grunt ranged from 84 to 91%, and for schoolmaster ranged from 94 to 99%. In St. Croix, classification success for French grunt was 95 to 96%, and for schoolmaster was 86 to 89%. The percentages of French grunt subadults collected from forereef stations in St. Croix, identified as having resided as juveniles in mangrove habitats in 2006 and 2007, were 40 and 68%, respectively, while for Puerto Rico, these percentages were 70 and 74%. By contrast, for schoolmaster almost 100% of all fish in both islands resided as juveniles in mangrove habitats in both years. This study contains the first direct evidence of postsettlement fish movement connecting mangrove habitats to the reef using otolith chemistry. KEY WORDS: Fish nursery· Otolith chemistry · Stable isotopes · Natural tags · Haemulon flavolineatum· Lutjanus apodus · Juvenile habitatResale or republication not permitted without written consent of the publisher Mar Ecol Prog Ser 402: 197-212, 2010 grove and seagrass meadows, and those different habitats are likely to vary in quality (Beck et al. 2001, Gillanders et al. 2003, Mumby et al. 2004. Determining the relative value of various nursery areas is important to both understanding the ecological roles of the different juvenile habitats and managing harvested fish populations and coastal resources. Identification of nursery habitats is particularly important when some of the nearshore habitats used by juvenile fish are vulnerable to degradation or loss (Beck et al. 2001, Adams & Ebersole 2002, Mumby et al. 2004, Gillanders 2005. Otolith chemistry is a powerful tool used to investigate movements and life history of fishes (Campana 1999, Gillanders et al. 2003, Elsdon et al. 2008. Chemical habitat tags in the otoliths of juvenile fish have been use...

Several authors state that foraging conditions and food web dynamics may be contributing to declines in Atlantic cod stocks. Therefore, it is essential to take a food web perspective to understand the complicated array of potential interactions affecting marine communities. The widely used Wisconsin Bioenergetics Model uses an energy-balance approach calculated on a daily time step and can be used to evaluate the effect of changes in prey resources on growth or food consumption. Bioenergetics models have been made for many important fishes within the Great Lakes. However, few have been developed for US Northeastern Continental Shelf fish species. Growth performance of Georges Bank and Gulf of Maine Atlantic cod during 2004 was examined using a bioenergetics model and available data on gut contents and growth of different ages. Growth efficiency, calculated from daily growth and consumption rates, was used as a measure of growth performance. Overall growth performance for Atlantic cod was significantly lower at Georges Bank than in Gulf of Maine. Monthly individual consumption demand and specific growth rates for Atlantic cod calculated from the bioenergetic model were significantly higher on Georges Bank than in the Gulf of Maine. Increasing water temperatures approached the upper limits of thermal tolerances for cod in Georges Bank, possibly leading to decreasing growth efficiencies. Growth efficiency of cod in the Gulf of Maine was less variable than on Georges Bank due to the more homogenous temperatures and energetic content of diets found in the former location.

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