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Fisheries Data (fisheries + data)

Distribution by Scientific Domains

Life Sciences	75%

Selected Abstracts

Recruitment patterns of six species of cyprinid fishes in the lower River Trent, England

ECOLOGY OF FRESHWATER FISH, Issue 2 2002
A. D. Nunn
Abstract,,,Fisheries data were collected for six species of 0-group cyprinid fishes from eight sites in the lower reaches of the River Trent, England, between May and October 1999 inclusive, using a micromesh seine net. Recruitment and growth patterns were observed via monthly length,frequency histograms and estimations of mean length. In the cases of roach and dace, growth was approximately linear through the summer, before declining in September and October. In the cases of chub and gudgeon, and to a lesser extent bream and bleak, however, there were suggestions of multiple recruitment events. It is argued that some of the fish species examined in the present study adopt fractional or protracted spawning strategies in the lower River Trent. [source]

GIS visualisation and analysis of mobile hydroacoustic fisheries data: a practical example

FISHERIES MANAGEMENT & ECOLOGY, Issue 6 2005
A. R. COLEY
Abstract, Hydroacoustic remote sensing of fish populations residing in large freshwater bodies has become a widely used and effective monitoring tool. However, easy visualisation of the data and effective analysis is more problematic. The use of GIS-based interpolations enables easy visualisation of survey data and an analysis tool for investigating fish populations. Three years of hydroacoustic surveys of Cardiff Bay in South Wales presented an opportunity to develop analysis and visualisation techniques. Inverse distance weighted (IDW) interpolation was used to show the potential of such techniques in analysing survey data both spatially (1-year survey) and temporally (by looking at the spatial changes between years). IDW was fairly successful in visualising the hydroacoustic data for Cardiff Bay. However, other techniques may improve on this initial work and provide improved analysis, total density estimates and statistically derived estimations of prediction error. [source]

Reorganization of a large marine ecosystem due to atmospheric and anthropogenic pressure: a discontinuous regime shift in the Central Baltic Sea

GLOBAL CHANGE BIOLOGY, Issue 6 2009
CHRISTIAN MÖLLMANN
Abstract Marine ecosystems such as the Baltic Sea are currently under strong atmospheric and anthropogenic pressure. Besides natural and human-induced changes in climate, major anthropogenic drivers such as overfishing and anthropogenic eutrophication are significantly affecting ecosystem structure and function. Recently, studies demonstrated the existence of alternative stable states in various terrestrial and aquatic ecosystems. These so-called ecosystem regime shifts have been explained mainly as a result of multiple causes, e.g. climatic regime shifts, overexploitation or a combination of both. The occurrence of ecosystem regime shifts has important management implications, as they can cause significant losses of ecological and economic resources. Because of hysteresis in ecosystem responses, restoring regimes considered as favourable may require drastic and expensive management actions. Also the Baltic Sea, the largest brackish water body in the world ocean, and its ecosystems are strongly affected by atmospheric and anthropogenic drivers. Here, we present results of an analysis of the state and development of the Central Baltic Sea ecosystem integrating hydroclimatic, nutrient, phyto- and zooplankton as well as fisheries data. Our analyses of 52 biotic and abiotic variables using multivariate statistics demonstrated a major reorganization of the ecosystem and identified two stable states between 1974 and 2005, separated by a transition period in 1988,1993. We show the change in Baltic ecosystem structure to have the characteristics of a discontinuous regime shift, initiated by climate-induced changes in the abiotic environment and stabilized by fisheries-induced feedback loops in the food web. Our results indicate the importance of maintaining the resilience of an ecosystem to atmospherically induced environmental change by reducing the anthropogenic impact. [source]

Fisheries, large-scale trade, and conservation of seahorses in Malaysia and Thailand

AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 4 2010
Allison L. Perry
Abstract 1.All seahorse species (genus Hippocampus) are listed under CITES Appendix II, requiring that exports of these fishes must be regulated for sustainability. Preliminary trade surveys and anecdotal reports suggested Malaysia and Thailand represented an important source for seahorses used globally in traditional medicine, curios, and aquarium display, but few historic trade or fisheries data are available. Baseline information about pre-CITES catch and trade is essential for managing seahorse fisheries and trade under CITES, and for understanding present-day effects of CITES regulation on the seahorse trade. 2.In 1998,1999, seahorse fisheries and trade in both countries were assessed by interviewing participants at many levels of the trade and corroborating those surveys with official trade documents. 3.Seahorses were found to be landed primarily as trawl bycatch. Malaysia's catch of 2900,kg year,1 was less than the estimated domestic consumption (5500,6000,kg year,1), whereas Thailand's catch of 6600,kg year,1 apparently far exceeded domestic consumption (,520,kg year,1). 4.Both countries imported seahorses from and exported to other Asian nations. Import statistics from Hong Kong SAR and Taiwan recorded maximum annual trade from Malaysia at 1280,kg year,1. Trade surveys indicated that Thailand exported at least 5000,kg annually (similar to the estimation of catch), but national Customs records reported 10,500,kg year,1 in exports, supported by official import records from Hong Kong SAR and Taiwan which indicated that Thailand was the source of up to 11,400,kg year,1. 5.Fishers and traders in both countries reported decreasing availability of seahorses, raising conservation concerns. These apparent declines, in combination with substantial domestic consumption, point towards the challenges that Malaysia and Thailand face in establishing sustainable levels of exports under CITES. Copyright © 2010 John Wiley & Sons, Ltd. [source]