An analysis of migratory salmonid catch effort data, derived from anglers' log books, 1991

1000 log books were issued to anglers of which 236 were returned, those from the rivers Derwent, Kent, Lune and Ribble accounted for the vast majority. The Derwent had the highest catch rate of these rivers: one salmon every 13.89 hours followed by the Lune, Kent and Ribble at 16.39, 18.87 and 35.71 hours, respectively. For sea trout the Lune, Derwent and Ribble had a catch rate of approximately one fish every 10.0 hours (9.8, 10.0 and 10.64 hours),and for the Kent one fish per 16.1 hours fished. Salmon angling visits were, in general,longer than those for sea trout being between 2 and 6 hours as opposed to 2 to 4 hours. On the majority of visits (>80%) no fish were caught and was the same for salmon and sea trout. For salmon the majority of fish were caught on fly, spinner or worm, and the least on prawn. For sea trout fly predominated. The majority of salmon caught were less than 91b in weight and were presumed to be grilse (1 sea winter). The majority of the sea trout caught weighed between 1 and 31b. The pattern of catch, effort, CPUE, abundance and catchability for salmon and sea trout were modelled using the data from the rivers Derwent, Kent and Lune. Flow significantly influenced catch, effort and catchability of salmon which had entered in a particular month. For sea trout flow was not significantly correlated with any of the dependent variables. The catchability coefficient for salmon, determined from the total number of fish, remained relatively constant over the period June to October indicating that CPUE was a reasonable measure of within season abundance. This was not found to be the case for sea trout.

Newport's mooring regulations: legal and policy analysis

The legal and policy issues facing Newport as it revises and implements its ordinances are numerous. Most of the issues have not been squarely resolved for Rhode Island. While Newport may take guidance from other states, it will be Rhode Island's task going forward to define the reach of its PTD as applied to some novel issues raised by mooring administration. The benefit of the flexibility of the PTD is allowing smaller units of government like Newport to define their regulatory goals based on a locally-tailored balancing test of competing interests facing scarce ocean resources. This report was designed to facilitate decision-maker discussion of how to strike that delicate balance.

Coarse and stillwater trout fisheries. Paper in evidence to the review of fisheries policy and legislation

This paper highlights the social and economic importance of coarse and stillwater trout fisheries and explains the UK Environment Agency's aim, its policies and processes, and its powers for managing and regulating these fisheries, concluding with reasoned proposals for change.

A coarse fish close season on canals. Paper in evidence to the review of fisheries policy and legislation. Paper number: EA-12

This paper gives the results of the Environment Agency's research into the canal close season to the Salmon and Freshwater Fisheries Review Group. It presents the findings of the research, explains why the research was undertaken and how it relates to the Agency's duties. The background for this report includes that angling representative bodies have long argued that the existing situation in which somecanals have a close season and others do not, is unsatisfactory.

Use of telemetric tracking to examine environmental influences on catch/effort indices. A case study of Atlantic Salmon (Salmo salar L.)in the R. Tywi, S. Wales

A case study of Atlantic Salmon runs into the R. Tyvi (S. Wales) is presented. Radio tracking of over 200 salmon in 1988 and 1989 has demonstrated that flow is an important factor in modifying both run timing and migratory success. Entry of salmon into the river is typically in response to flow events, and periods of low falling flows delay entry and may directly result in reduced runs into the river. Delayed entry may also increase the proportion of the run migrating after the end of both rod and net fishing seasons. The implications of these results for net and rod catch and catch/effort data are discussed, using both statutory reported catch data and data from specific catch/effort studies. Flow is demonstrated to be a dominant factor in determining the within-season distribution of rod catch and catch/effort during low-flow years. Estuarial seine net catch and catch/effort tend to be controlled more by time of return than by flow although low flows may delay runs. Annual reported rod catch is correlated with flow, which controls in season availability, catchability and consequently the amount of fishing effort. Use of catch or catch/effort data should take account of inter-year variations in flow and other environmental factors. Although catch and catch/effort are valuable indicators of fishery performance, they are inadequate to represent changing stock levels.

Avian piscivores: basis for policy.

In Britain, many birds eat fish in fresh waters but only three species, cormorant, red-breasted merganser and goosander, are commonly perceived to present serious problems for freshwater fisheries. Complaints are mainly that cormorants eat large fish and that all three bird species eat so many juvenile fish, that there are subsequently fewer fish to be harvested or angled, but also that persistent predation by birds changes fish behaviour so that they are less 'catchable'. To this end, this report reviews existing information on the current status, foraging ecology, and population biology of the three bird species as background to their potential impact on fisheries. Discusses fish population dynamics within the context of predation effects. Reviews existing experimental evidence for impacts on fish populations and fisheries; and describes current legislation, discusses potential criteria for serious damage to a fishery, and suggests ways forward for NRA policy and research.

Catch rates and demographics of loggerhead sea turtles (Caretta caretta) captured from the Charleston, South Carolina, shipping channel during the period of mandatory use of turtle excluder devices (TEDs)

Trawling was conducted in the Charleston, South Carolina, shipping channel between May and August during 2004–07 to evaluate loggerhead sea turtle (Caretta caretta) catch rates and demographic distributions. Two hundred and twenty individual loggerheads were captured in 432 trawling events during eight sampling periods lasting 2–10 days each. Catch was analyzed by using a generalized linear model. Data were fitted to a negative binomial distribution with the log of standardized sampling effort (i.e., an hour of sampling with a net head rope length standardized to 30.5 m) for each event treated as an offset term. Among 21 variables, factors, and interactions, five terms were significant in the final model, which accounted for 45% of model deviance. Highly significant differences in catch were noted among sampling periods and sampling locations within the channel, with greatest catch furthest seaward consistent with historical observations. Loggerhead sea turtle catch rates in 2004–07 were greater than in 1991–92 when mandatory use of turtle excluder devices was beginning to be phased in. Concurrent with increased catch rates, loggerheads captured in 2004–07 were larger than in 1991–92. Eighty-five percent of loggerheads captured were ≤75.0 cm straight-line carapace length (nuchal notch to tip of carapace) and there was a 3.9:1 female-to-male bias, consistent with limited data for this location two decades earlier. Only juvenile loggerheads ≤75.0 cm possessed haplotypes other than CC-A01 or CC-A02 that dominate in the region. Six rare and one un-described haplotype were predominantly found in June 2004.

Changes in catch rates and length and age at maturity, but not growth, of an estuarine plotosid (Cnidoglanis macrocephalus) after heavy fishing

The hypothesis that heavy fishing pressure has led to changes in the biological characteristics of the estuary cobbler (Cnidoglanis macrocephalus) was tested in a large seasonally open estuary in southwestern Australia, where this species completes its life cycle and is the most valuable commercial fish species. Comparisons were made between seasonal data collected for this plotosid (eeltail catfish) in Wilson Inlet during 2005–08 and those recorded with the same fishery-independent sampling regime during 1987–89. These comparisons show that the proportions of larger and older individuals and the catch rates in the more recent period were far lower, i.e., they constituted reductions of 40% for fish ≥430 mm total length, 62% for fish ≥4 years of age, and 80% for catch rate. In addition, total mortality and fishing-induced mortality estimates increased by factors of ~2 and 2.5, respectively. The indications that the abundance and proportion of older C. macrocephalus declined between the two periods are consistent with the perception of long-term commercial fishermen and their shift toward using a smaller maximum gill net mesh to target this species. The sustained heavy fishing pressure on C. macrocephalus between 1987–89 and 2005–08 was accompanied by a marked reduction in length and age at maturity of this species. The shift in probabilistic maturation reaction norms toward smaller fish in 2005–08 and the lack of a conspicuous change in growth between the two periods indicate that the maturity changes were related to fishery-induced evolution rather than to compensatory responses to reduced fish densities.

Sistema inteligente para determinação de limite de crédito

A presente dissertação trata da estipulação de limite de crédito para empresas clientes, de modo automático, com o uso de técnicas de Inteligência Computacional, especificamente redes neurais artificiais (RNA). Na análise de crédito as duas situações mais críticas são a liberação do crédito, de acordo com o perfil do cliente, e a manutenção deste limite ao longo do tempo de acordo com o histórico do cliente. O objeto desta dissertação visa a automação da estipulação do limite de crédito, implementando uma RNA que possa aprender com situações já ocorridas com outros clientes de perfil parecido e que seja capaz de tomar decisões baseando-se na política de crédito apreendida com um Analista de Crédito. O objetivo é tornar o sistema de crédito mais seguro para o credor, pois uma análise correta de crédito de um cliente reduz consideravelmente os índices de inadimplência e mantém as vendas num patamar ótimo. Para essa análise, utilizouse a linguagem de programação VB.Net para o sistema de cadastro e se utilizou do MatLab para treinamento das RNAs. A dissertação apresenta um estudo de caso, onde mostra a forma de aplicação deste software para a análise de crédito. Os resultados obtidos aplicando-se as técnicas de RNAs foram satisfatórias indicando um caminho eficiente para a determinação do limite de crédito.

Efficiency and catch dynamics of collapsible square and conical pots used in the red king crab (Paralithodes camtschaticus) fishery

We compared the capture efficiency and catch dynamics of collapsible square and conical pots used in resource assessment and harvesting of red king crabs (Paralithodes camtschaticus [Tilesius, 1815]) in the Barents Sea. After two days of soaking, square pots caught three times as many crabs as conical pots, and their catches consisted of a higher proportion of male crabs and male crabs larger than 160 mm carapace length compared to the catches in the conical pots. Catches in the square pots did not increase as soak times were increased beyond two days, which indicates equilibrium between the rate of entries into and the rate of exits from the pots. Catches in conical pots, however, increased with increasing soak times up to eight days, the longest soak time examined in this study. These findings demonstrate the higher efficiency of square pots and the importance of understanding catch dynamics when making population assessments based on catchper-unit-of-effort data. The favorable catch characteristics and handling properties of the collapsible square pot may make this pot design suitable for other crab fisheries, as well.