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J Hooks (j + hook)
Selected AbstractsReducing sea turtle by-catch in pelagic longline fisheriesFISH AND FISHERIES, Issue 1 2006Eric Gilman Abstract Reducing by-catch of sea turtles in pelagic longline fisheries, in concert with activities to reduce other anthropogenic sources of mortality, may contribute to the recovery of marine turtle populations. Here, we review research on strategies to reduce sea turtle by-catch. Due to the state of management regimes in most longline fisheries, strategies to reduce turtle interactions must not only be effective but also must be commercially viable. Because most research has been initiated only recently, many results are not yet peer-reviewed, published or readily accessible. Moreover, most experiments have small sample sizes and have been conducted over only a few seasons in a small number of fisheries; many study designs preclude drawing conclusions about the independent effect of single factors on turtle by-catch and target catch rates; and few studies consider effects on other by-catch species. In the US North Atlantic longline swordfish fishery, 4.9-cm wide circle hooks with fish bait significantly reduced sea turtle by-catch rates and the proportion of hard-shell turtles that swallowed hooks vs. being hooked in the mouth compared to 4.0-cm wide J hooks with squid bait without compromising commercial viability for some target species. But these large circle hooks might not be effective or economically viable in other longline fisheries. The effectiveness and commercial viability of a turtle avoidance strategy may be fishery-specific, depending on the size and species of turtles and target fish and other differences between fleets. Testing of turtle avoidance methods in individual fleets may therefore be necessary. It is a priority to conduct trials in longline fleets that set gear shallow, those overlapping the most threatened turtle populations and fleets overlapping high densities of turtles such as those fishing near breeding colonies. In addition to trials using large 4.9-cm wide circle hooks in place of smaller J and Japan tuna hooks, other fishing strategies are under assessment. These include: (i) using small circle hooks (, 4.6-cm narrowest width) in place of smaller J and Japan tuna hooks; (ii) setting gear below turtle-abundant depths; (iii) single hooking fish bait vs. multiple hook threading; (iv) reducing gear soak time and retrieval during daytime; and (v) avoiding by-catch hotspots through fleet communication programmes and area and seasonal closures. [source] Are circle hooks effective in reducing incidental captures of loggerhead sea turtles in a Mediterranean longline fishery?AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 7 2009Susanna Piovano Abstract 1.A known fishing hot spot for loggerhead sea turtles (Caretta caretta) in the Mediterranean Sea is in the waters of the Strait of Sicily where interactions with fish hooks and branchlines are believed to be a major cause of mortality for sea turtles. 2.Hooks with different shapes but a similar gape width (circle hook size 16/0 vs J hook size 2) were tested in order to determine the potential effectiveness of the hook design to both reduce sea turtle capture as well as to maintain acceptable levels of target species capture rates in a shallow-set longline swordfish fishery in the Mediterranean. 3.Seven experimental fishing trips, 30,000 hooks total, were conducted on a single commercial fishing vessel (18,m in length) in the Strait of Sicily during the months of July through October over a period of three years from 2005 to 2007. Circle and J hooks were alternated along the mainline. 4.A total of 26 sea turtles were hooked, all immature-size Caretta caretta. Turtles were caught at a statistically greater frequency on J hooks than on circle hooks. The capture rate, weight, and upper jaw fork length of the target species were not significantly different between the two types of hooks employed. 5.Five sea turtles swallowed the hook and in all such cases these were J type. Circle hooks tended to be located externally and were more easily detected by fishermen, and could be removed with the correct dehooking action before returning the turtle to the sea. 6.These findings suggest that 16/0 circle hooks can effectively reduce the incidental capture of immature loggerhead sea turtles in a Mediterranean swordfish longline fishery without affecting the catch size of the target species. Copyright © 2009 John Wiley & Sons, Ltd. [source] Circle hooks, ,J' hooks and drop-back time: a hook performance study of the south Florida recreational live-bait fishery for sailfish, Istiophorus platypterusFISHERIES MANAGEMENT & ECOLOGY, Issue 2 2007E. D. PRINCE Abstract, This study evaluates the performance of two types of non-offset circle hooks (traditional and non-traditional) and a similar-sized ,J' hook commonly used in the south Florida recreational live-bait fishery for Atlantic sailfish, Istiophorus platypterus (Shaw). A total of 766 sailfish were caught off south Florida (Jupiter to Key West, FL, USA) to assess hook performance and drop-back time, which is the interval between the fish's initial strike and exertion of pressure by the fisher to engage the hook. Four drop-back intervals were examined (0,5, 6,10, 11,15 and >15 s), and hook performance was assessed in terms of proportions of successful catch, undesirable hook locations, bleeding events and undesirable release condition associated with physical hook damage and trauma. In terms of hook performance, the traditionally-shaped circle hook had the greatest conservation benefit for survival after release. In addition, this was the only hook type tested that performed well during each drop-back interval for all performance metrics. Conversely, ,J' hooks resulted in higher proportions of undesirable hook locations (as much as twofold), bleeding and fish released in undesirable condition, particularly during long drop-back intervals. Non-traditional circle hooks had performance results intermediate to the other hook types, but also had the worst performance relative to undesirable release condition during the first two drop-back intervals. Choice of hook type and drop-back interval can significantly change hook wounding, and different models of non-offset circle hooks should not be assumed to perform equivalently. [source] | ||||||||||