Standardization of catch and effort data in a spatially-structured shark fishery
TL;DR: The methods used to develop catch rate based indices of relative abundance for the school shark Galeorhinus galeus resource off southern Australia are outlined in this paper, which are based on fitting generalized linear models to catch and effort data for several regions in this fishery.
About: This article is published in Fisheries Research.The article was published on 2000-03-01. It has received 172 citations till now.
Citations
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TL;DR: A review of the state of the art in the methods for standardizing catch and effort data can be found in this paper, which outlines the major estimation approaches being applied, how to identify and select appropriate explanatory variables, and how standardized catch rate can be used when conducting stock assessments.
1,154 citations
TL;DR: This paper provides an overview of the modelling process using generalized linear models, generalized additive models (GAMs) and generalized linear mixed models (GLMMs), especially as they are applied within fisheries research.
399 citations
TL;DR: The zero-inflated negative binomial (ZINB) regression model with smoothing is introduced for modeling count data with many zero-valued observations, and its use is illustrated with shark bycatch data from the eastern Pacific Ocean tuna purse-seine fishery for 1994-2004.
223 citations
TL;DR: In this article, the authors argue that these conclusions have been overstated because: (1) the analyses were based on a limited number of data sets, (2) the data sets themselves are inadequate to describe the status of all shark populations in the northwest Atlantic Ocean and Gulf of Mexico reported in these studies, and (3) available data sets that could produce different concl...
Abstract: Increasing fishing pressure on sharks stocks over recent decades has resulted in declines of many populations and led to increasing concerns for their conservation. The extent of these declines, however, has been highly variable—the result of the level of fishing, ocean conditions, and the life history of individual species. Two recent articles have described the collapse and possible extirpation of shark populations in the northwest Atlantic Ocean and Gulf of Mexico. Herein, we examine the results of these two papers commenting on the data sets used, comparing them to other available data sets, and critically evaluating the analyses and conclusions. We argue that these conclusions have been overstated because: (1) the analyses were based on a limited number of data sets, (2) the data sets themselves are inadequate to describe the status of all shark populations in the northwest Atlantic Ocean and Gulf of Mexico reported in these studies, (3) available data sets that could produce different concl...
174 citations
Cites methods from "Standardization of catch and effort..."
...The reliability of each CPUE time series depends on the type (e.g., commercial, recreational, scientific), the generalized linear model and error structure assumed and applied to those data (e.g., Punt et al. 2000), and the relative weight assigned to each series....
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TL;DR: While nursery area protection should remain a component in shark management strategies it will be critical to link early life stage conservation with management strategies that encompass older individuals residing outside nurseries if effective management is to be achieved.
Abstract: Concern over declining shark populations has led to an intense interest in their conservation and management. Due to the difficulties involved in managing adult sharks, focus has been placed on young juvenile and neonate age classes that inhabit discrete inshore nursery areas. However, past confusion over what qualifies as a nursery habitat has led to the identification of vast coastal areas as nurseries, making conservation unfeasible. With the establishment of more discerning criteria for nursery area identification such concerns have been somewhat alleviated, but while effort has been put into defining, identifying, mapping, and in some cases protecting nursery areas, little attention has been paid to the practical value of nurseries for the recovery of exploited shark populations. Often neonate and young juveniles are considered the most critical age classes in terms of population stability/recovery, but evidence is mounting that suggests life stages outside the nursery may be more important in this regard. While nursery area protection should remain a component in shark management strategies it will be critical to link early life stage conservation with management strategies that encompass older individuals residing outside nurseries if effective management is to be achieved.
165 citations
Cites background from "Standardization of catch and effort..."
...Despite these efforts, by the late 1980s G. galeus populations had been severely depleted (see Punt et al. 2000 for a detailed discussion of declining catch rates of G. galeus)....
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...Concurrently, the standardized catch rate for G. galeus declined by over 50% from 1983 to 1997 (Punt et al. 2000)....
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References
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Book•
01 Jan 1992
TL;DR: Quantitative fisheries stock assessment as mentioned in this paper, Quantitative fishery stock assessment: Quantitative fishes stock assessment, Quantitative fish stock assessment and stock assessment in the field of fishery management.
Abstract: Quantitative fisheries stock assessment : , Quantitative fisheries stock assessment : , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
1,581 citations
Book•
01 Jun 1991
TL;DR: An essential tool for conservation biologists trying to save threatened sharks, now under siege worldwide, this marvelous volume will also appeal to fish biologists, divers, naturalists, commercial and recreational fishermen, and anyone with an appreciation for these ancient evolutionary survivors.
Abstract: The waters around Australia are home to the greatest diversity of sharks and rays on Earth. Spookfish, numbfish, stingarees, fiddler rays and cookie-cutter sharks are just some of the 322 shark, ray and chimaerid species illustrated in the latest edition of Sharks and Rays of Australia. Australia's sharks, rays and chimaerids - collectively known as Chondrichthyans - are just as intriguing as their names suggest. Their eclectic colours, shapes and patterns reflect environments ranging from remote estuaries to ocean depths. Their new descriptions, and their striking portraits by watercolourist Roger Swainston, will help to guide the identification and conservation of these diverse species. The first edition of Sharks and Rays of Australia was produced in 1994. Since then, 29 species have been discovered in Australian seas and more than 100 species have been named and formally described. As well as documenting these advances, the new edition includes updated species classifications and descriptions, distribution maps, line illustrations by Georgina Davis, family keys and outlines of Chondrichthyan biology and interactions with humans. The book catalogues a rich seam of Australia's marine biodiversity, providing an indispensible compendium for scientists and a baseline reference for the fishing industry. Sharks and Rays of Australia is an essential reference for professional and recreational fishermen, divers, naturalists, students, fish and conservation biologists, and anyone interested in sharks and rays.
1,190 citations
TL;DR: This paper reviews the use of shark products, the effects of fishing on shark populations of the world, and recent developments in assessment of shark fishery stocks.
Abstract: Sharks and other chondrichthyans are often described as long lived, slow growing and producing few offspring. These biological characteristics, together with the common assumption that recruitment is directly related to stock, and pessimistic stock prognoses obtained from application of demographic analysis, have led to doubts that sharks can be harvested sustainably. Developed over the past 40 or so years from studies of only a few shark species, these doubts have been reinforced by declining catch rates in industrial, artisanal and recreational fisheries and in fishing programmes designed to reduce the risk of sharks attacking humans at bathing beaches. However, more recent studies and application of modelling techniques allowing for density-dependent responses to the effects of stock reduction indicate that shark stocks can be harvested sustainably and, if carefully managed, can provide very stable fisheries. It is now understood that some species (such as Galeorhinus galeus, Carcharhinus plumbeus, Carcharodon carcharias and several species of dogfish) have low productivity, whereas other species (such as Mustelus antarcticus, Rhizoprionodon terraenovae, Sphyrna tiburo and Prionace glauca) have higher productivity. This paper reviews the use of shark products, the effects of fishing on shark populations of the world, and recent developments in assessment of shark fishery stocks.
380 citations
TL;DR: In this paper, the results of Aitchison (1955, Journal of the American Statistical Association 50, 901-908) on the estimation of the mean and variance of a distribution with a discrete probability mass at zero are applied and extended to give an estimate of the variance associated with the estimate.
Abstract: The data from marine surveys often contain a large proportion of zeros. Treating the zeros separately can lead, in some cases, to more efficient estimators of abundance. To this end, the results of Aitchison (1955, Journal of the American Statistical Association 50, 901-908) on the estimation of the mean and variance of a distribution with a discrete probability mass at zero are applied and extended to give an estimate of the variance associated with the estimate of the mean. It is shown that under some conditions these are minimum variance unbiased estimators. The case in which the nonzero values are lognormally distributed is examined in detail and applied to an ichthyoplankton survey.
361 citations