摘要:

This review focuses on the influence of salinity on freshwater fishes in coastal rivers and estuaries of the southeastern U.S. Influences of salinity on freshwater fish species can be explained partly through responses evidenced by behavior, physiology, growth, reproduction, and food habits during all aspects of life history. Factors influencing the rate of salinity change affect the community structure and dynamics of freshwater fishes in brackish environments. Our understanding of the relation between salinity and the life history of freshwater fishes is limited because little ecological research has been conducted in low‐salinity habitats that we consider an “interface”; between freshwater streams and the estuary proper. Much of the available data are descriptive in nature and describe best general patterns, but more specific studies are required to better determine the influence of salinity on freshwater fishes. Improved understanding of the influence of human‐induced changes on the productivity and viability of these important systems will require a new research focus.

ISSN:1064-1262    

DOI:10.1080/10641269409388554

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Length‐limit regulations and promotion of catch‐and‐release fishing have become increasingly important management approaches for recreational fisheries. We review‐studies on catch‐and‐release (hooking) mortality gathered from the existing fisheries literature and from a survey of fisheries management agencies in all 50 states, the U.S. government, all Canadian provinces, and selected academic and research institutions. We identified hooking mortality estimates for 32 taxa. Most studies dealt with salmonids, centrarchids (especially black basses,Micropterusspp.), and percids (especially walleye,Stizostedion vitreum). Within and among species, differences in percent mortality were reported in association with bait type (artificial vs. natural), hook type (number of hooks, hook size, and barbs), season/ temperature, water depth (depressurization), anatomical location of hook wound, and individual size. Although most hooking mortalities occur within 24 h, the use of initial plus delayed mortality provides a more complete estimate of mortality. Single hooks (especially when used in conjunction with natural baits) resulted in higher mortalities than treble hooks. Environmental conditions (notably high water temperature and low dissolved oxygen) are important to overall mortality related to hooking, playing, and handling. Mortalities were highly variable; occasionally exceeding 30% among red drum (Sciaenops ocellatus), smallmouth bass (M.dolomieu), largemouth bass (M.salmoides), cutthroat trout(Oncorhynchus clarki), and catfishes (Ictaluridae), and 68% among spotted seatrout (Cynoscion nebulosus), bluegills (Lepomis macrocbirus), crappies, (Pomoxisspp.), striped bass (Morqne saxatilis), and coho salmon (O.kisutch). Lake trout (Salvelinus namaycush) and pikes (Esoddae) had mortalities under 15%. The many variables potentially affecting hooking mortality may make optimal management of particular species and water bodies difficult using regional‐level (e.g., statewide) management regulations.

ISSN:1064-1262    

DOI:10.1080/10641269409388555

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Application of the concept of ecosystems to fisheries management would provide managers with a useful conceptual framework within which they may (1) absorb specific scientific advice, (2) anticipate probable resource responses to fishing perturbations, (3) anticipate species interactions, and (4) anticipate the effects of management measures. Ecosystems in general encompass three major components: (1) species life history strategies, (2) the evolution of communities, and (3) hierarchic, rate‐regulating structures. The interrelation of these components and apparent examples in fisheries ecosystems are reviewed. Most fisheries experience a reversal of the natural evolution of ecosystems dynamics, that is, fishing induces greater frequency and amplitude of variations of specific components of the system. An understanding by managers of the functions and interrelations of the basic components of systems clarifies the reasons for the typical response of fisheries ecosystems to the fishing effort. The implications of ecosystems characteristics for fisheries managers are also briefly considered.

ISSN:1064-1262    

DOI:10.1080/10641269409388556

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor