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In many fisheries, some component of the catch is usually released. Quantifying the effects of capture and release on fish survival is critical for determining which practices are sustainable, particularly for threatened species. Using a standardized fishing technique, we studied sublethal (blood physiology and reflex impairment assessment) and lethal (post-release mortality with satellite tags) outcomes of fishing stress on 5 species of coastal sharks (great hammerhead, bull, blacktip, lemon, and tiger). Species-specific differences were detected in whole blood lactate, partial pressure of carbon dioxide, and pH values, with lactate emerging as the sole parameter to be significantly affected by increasing hooking duration and shark size. Species-specific differences in reflex impairment were also found; however, we did not detect any significant relationships between reflex impairment and hooking duration. Taken together, we ranked each species according to degree of stress response, from most to least disturbed, as follows: hammerhead shark > blacktip shark > bull shark > lemon shark > tiger shark. Satellite tagging data revealed that nearly 100% of all tracked tiger sharks reported for at least 4 wk after release, which was significantly higher than bull (74.1%) and great hammerhead (53.6%) sharks. We discuss which mechanisms may lead to species-specific differences in sensitivity to fishing and suggest that observed variation in responses may be influenced by ecological and evolutionary phenomena. Moreover, our results show that certain species (i.e. hammerhead sharks in this study) are inherently vulnerable to capture stress and mortality resulting from fisheries interactions and should receive additional attention in future conservation strategies.

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Oxygen minimum zones (OMZs) below near-surface optimums in the eastern tropical seas are among the largest contiguous areas of naturally occurring hypoxia in the world oceans, and are predicted to expand and shoal with global warming. In the eastern tropical Pacific (ETP), the surface mixed layer is defined by a shallow thermocline above a barrier of cold hypoxic water, where dissolved oxygen levels are £3.5 mL L )1 . This thermocline (25-50 m) constitutes a lower hypoxic habitat boundary for high oxygen demand tropical pelagic billfish and tunas (i.e., habitat compression). To evaluate similar oceanographic conditions found in the eastern tropical Atlantic (ETA), we compared vertical habitat use of 32 sailfish (Istiophorus platypterus) and 47 blue marlin (Makaira nigricans) monitored with pop-up satellite archival tags in the ETA and western North Atlantic (WNA). Both species spent significantly greater proportions of their time in near-surface waters when inside the ETA than when in the WNA. We contend that the near-surface density of billfish and tunas increases as a consequence of the ETA OMZ, therefore increasing their vulnerability to overexploitation by surface gears. Because the ETA OMZ encompasses nearly all Atlantic equatorial waters, the potential impacts of overexploitation are a concern. Considering the obvious differences in catchability inside and outside the compression zones, it seems essential to standardize these catch rates separately to minimize inaccuracies in stock assessments for these species. This is especially true in light of global warming, which will likely exacerbate future compression impacts.

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Release and recovery files from the world's five major constituent-based billfish (Istiophoridae) tagging programs were assembled into a single composite database. Data sources included the National Marine Fisheries Service's (NMFS) Cooperative Tagging Center (MIA) in the Atlantic Ocean, the NMFS's Cooperative Billfish Tagging Program (LJA) in the Pacific and Indian Oceans, the Australian Cooperative Tagging Program in the Pacific and Indian Oceans, the New Zealand Cooperative Game Fish Tagging Program in the Pacific Ocean, and The Billfish Foundation's (TBF) tagging program in the Atlantic, Pacific and Indian Oceans. Results for the main target species, including black marlin (Makaira indica), blue marlin (Makaira nigricans), white marlin (Tetrapturus albidus), striped marlin (Tetrapturus audax) and sailfish (Istiophorus platypterus) were compared and contrasted based on species, ocean body and tagging program. A total of over 317 000 billfish have been tagged and released, and 4122 have been recovered since 1954. Tag recovery percentages were generally higher for a recently developed doublebarb nylon anchor tag compared with the typically used stainless steel dart tag. Greatest distances moved were largest for blue marlin and black marlin, followed by striped marlin, white marlin and sailfish. The TBF program had the highest tag recovery percentages for white marlin (2.4%) and blue marlin (1.7%), whereas the MIA program had the highest percentage recovery for sailfish (1.8%). The LJA program had the highest recovery percentages for black marlin (1.9%) and striped marlin (1.4%). The annual number of releases and recoveries for each target species tended to increase over the time series, particularly during the last decade. Cyclic annual movement patterns and/or seasonal site fidelity were evident for black marlin and white marlin. The data suggest that tag recovery percentages can be affected by tag type, reporting rate, localized fishing activities, outreach activities, and a variety of logistical issues indirectly related to size of ocean body. The efficiencies of the tagging programs are compared and recommendations are made to improve the programs. The composite tagging database provides the opportunity for a more comprehensive evaluation of the data and tagging programs than has previously been possible by examining the individual programs in isolation. The main advantage of constituent-based tagging programs is that large numbers of billfish can be tagged at a minimum cost. The main drawbacks are a lack of control over the tagging event and return of recovery data. Constituent-based tagging programs provide essential data on billfish movement and biology, and should be expanded and improved to meet the increasing need for this information.

Many fishes are thought to make diel, seasonal and/or ontogenetic migrations among seagrass, mangrove, and coral reef habitats. However, most evidence of such movement has been inferred from density and size structure differences among these habitats in tropical waters. The aim of the present study was to directly evaluate multiple habitat use by an ecologically and economically important reef fish, the gray snapper Lutjanus griseus, in subtropical waters. An integrated set of activities was conducted, including tagging and tracking of individuals and underwater video photography to examine the spatial and temporal dynamics of movements among neighboring mangrove, seagrass, and coral reef habitats in the northern Florida Keys, USA. Results of ultrasonic acoustic and mini-archival tagging indicated that L. griseus exhibits: (1) a distinct diel migration pattern, whereby shallow seagrass beds are frequented nocturnally and mangroves and other habitats with complex structure are occupied diurnally, and (2) bay-to-ocean movement, occurring during the known spawning season of L. griseus in this region. Video photography confirmed diel movement among seagrass and mangrove habitats. Results of this subtropical study corroborate direct and indirect evidence obtained in tropical waters of multiple inshore habitat use by L. griseus, as well as its seasonal movement into or towards offshore reefs. For resource managers charged with designing and implementing management plans for subtropical coastal habitats and fisheries, our findings provide direct support for the strategy of conserving both inshore seagrass and mangrove habitats as well as offshore coral reefs.KEY WORDS: Diel · Seasonal · Gray snapper · Movement · Mangrove · Seagrass · Reef · Acoustic tagging · Underwater video Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 380: [255][256][257][258][259][260][261][262][263][264][265][266][267][268][269] 2009 structure (e.g. Cocheret de la Morinière et al. 2002, Nagelkerken 2007, dietary isotopes, and gut content analysis (Harrigan et al. 1989, Cocheret de la Morinière et al. 2003 or from otolith microchemistry (Chittaro et al. 2004). Recent work in Atlantic and Caribbean waters strongly suggests mangrove and seagrass 'back-reef' areas are a critical ontogenetic link in the life cycle of a number of coral reef fishes, serving as important nurseries for juveniles (e.g. Nagelkerken et al. 2000, Serafy et al. 2003, Mumby et al. 2004, Adams et al. 2006, Dorenbosch et al. 2007). Three recent reviews examining mangroves as fish habitat (Faunce & Serafy 2006, Nagelkerken 2007, Nagelkerken et al. 2008 have noted the dearth of direct evidence of fish movement among mangroves and other coastal habitats. Such species-specific data are needed to begin to quantify the contributions made by adjacent, shallow-water habitats in the life cycles and sustainability of managed fish species (Beck et al. 2001).Nearshore mangrove and seagrass habitats along the southern Florida (USA...