			Home About us Contact

Fishing Strategies (fishing + strategy)

Distribution by Scientific Domains

Earth and Environmental Science	75%

Selected Abstracts

Interactions between fishing strategies of Nephrops trawlers in the Bay of Biscay and Norway lobster diel activity patterns

FISHERIES MANAGEMENT & ECOLOGY, Issue 1 2008
V. M. TRENKEL
Abstract, Norway lobster, Nephrops norvegicus (L.), in the Bay of Biscay exhibited diel activity patterns with more individuals outside their burrows at dawn and dusk, increasing catchability at these times. Data from an on board observer programme on Nephrops trawlers between 2002 and 2005 were used to assess variability in catchability in commercial catches. Catch numbers per haul varied spatially and between months, but no signal for diel variations was found. Fishing strategies developed by the Nephrops trawlers had several components. On a seasonal level, they started around sunrise. On a haul level, haul duration decreased from haul to haul, with the longest hauls taking place at the time of the highest catchability. By-catch of hake, Merluccius merluccius (L.), increased more than proportionally with haul duration. [source]

Reducing sea turtle by-catch in pelagic longline fisheries

FISH AND FISHERIES, Issue 1 2006
Eric 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 Because most research has been initiated only recently, many results are not yet peer-reviewed, published or readily accessible.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]

Interactions between fishing strategies of Nephrops trawlers in the Bay of Biscay and Norway lobster diel activity patterns

An ecosystem modelling approach to deriving viable harvest strategies for multispecies management of the Northern Gulf of California

AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 4 2009
Diego Lercari
Abstract 1.An ecosystem analysis was developed focusing on resource exploitation and biodiversity conservation for the Northern Gulf of California. The main tools employed were a trophic ecosystem model and time dynamic simulations. 2.The ecosystem was represented by an Ecopath model that included 34 functional groups, from primary producers to top predators. It included relevant species in the area such as commercially important shrimp (e.g. Litopenaeus stylirostris) and highly endangered species (Phocoena sinus and Totoaba macdonaldi). 3.Temporal simulations of changing fishing effort allowed the evaluation of fishing impact on the ecosystem components and, particularly, on protected species. Formal optimization methods were applied with the purpose of searching viable temporal patterns of fishing effort that might minimize social, economic and conservationist conflicts in the area. 4.The results of those simulations showed the capability of the model to represent reference temporal series of relative biomass. The search for viable fishing strategies resulted in effort allocation consistent with those proposed by other studies; that is, a decrease in the industrial shrimp fleet (35,65%), a decrease in the gillnet fishing fleet (52,57%), and an increase of the artisanal shrimp fishery (63,222%). 5.The main conflicts in the Northern Gulf of California seem to take place between social and conservation interests, while the economic and ecological benefits seem to be relatively independent. The next steps towards conflict resolution and ecosystem management should consider the design and operation of MPAs already established in the region. Copyright © 2008 John Wiley & Sons, Ltd. [source]