Noncellular nonspecific defence mechanisms of fish

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, Micropterus spp.), 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 ...

Hooking mortality: A review for recreational fisheries

The mortality of discarded fish bycatch is an important issue in fisheries management and, because it is generally unmeasured, represents a large source of uncertainty in estimates of fishing mortality worldwide. Develop - ment of accurate measures of discard mortality requires fundamental knowledge, based on principles of bycatch stressor action, of why discarded fish die. To date, discard mortality studies in the field have focused on capture stressors. Recent laboratory discard experiments have demonstrated the significant role of environmental factors, size- and species-related sensitivity to stressors, and interactions of stressors, which increase mortality. In addition, delayed mortality was an important consideration in experimental design. The discard mortality problem is best addressed through a combination of laboratory investigation of classes of bycatch stressors to develop knowledge of key principles of bycatch stressor action and field experiments under realistic fishing conditions to verify our understanding and make predictions of discard mortality. This article makes the case for a broader ecological perspective on discard mortality that includes a suite of environmental and biological factors that may interact with capture stressors to increase stress and mortality.

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Key principles for understanding fish bycatch discard mortality

The role of phagocytes in the protective mechanisms of fish

Non-typhoidal Salmonella represents an important human and animal pathogen world-wide. Most human salmonellosis cases are foodborne, but each year infections are also acquired through direct or indirect animal contact in homes, veterinary clinics, zoological gardens, farm environments or other public, professional or private settings. Clinically affected animals may exhibit a higher prevalence of shedding than apparently healthy animals, but both can shed Salmonella over long periods of time. In addition, environmental contamination and indirect transmission through contaminated food and water may complicate control efforts. The public health risk varies by animal species, age group, husbandry practice and health status, and certain human subpopulations are at a heightened risk of infection due to biological or behavioral risk factors. Some serotypes such as Salmonella Dublin are adapted to individual host species, while others, for instance Salmonella Typhimurium, readily infect a broad range of host species, but the potential implications for human health are currently unclear. Basic hygiene practices and the implementation of scientifically based management strategies can efficiently mitigate the risks associated with animal contacts. However, the general public is frequently unaware of the specific disease risks involved, and high-risk behaviors are common. Here we describe the epidemiology and serotype distribution of Salmonella in a variety of host species. In addition, we review our current understanding of the public health risks associated with different types of contacts between humans and animals in public, professional or private settings, and, where appropriate, discuss potential risk mitigation strategies.

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Animal contact as a source of human non-typhoidal salmonellosis

Supported in part by a grant from the National Marine Fisheries Service ... Public Law 88-309. Includes index. Bibliography: p. 86-90. Also available in microfilm under: State agricultural papers.

Anatomy and histology of the channel catfish

The ability of the peripherial blood phagocytes from channel catfish, ictaluruspunctatus, to produce chemiluminescence (CL) following ingestion of the enteric pathogen Edwardsiellaictaluri was evaluated under a variety of opsonic and temperature conditions. The CL response was influenced by the concentration of immune serum used to opsonize the bacteria as well as the presence of nonspecific, heat labile opsonins. Peak light emissions were diminished and the time to peak response was increased with a reduction in temperature. Temperature-mediated changes in CL activity was accompanied by a corresponding change in intracellular killing. The addition of the metabolic inhibitors superoxide dismutase or sodium azide resulted in a reduction in CL and intracellular killing.

Chemiluminescence by peripheral blood phagocytes from channel catfish: Function of opson in and temperature

Edwardsiella ictaluri from walking catfish, Clarias batrachus L., in Thailand

Survival of angled largemouth bass Micropterus salmoides held in live wells for 3–9 h, with and without a water conditioner, was compared to largemouth bass released within 30 min (immediate release) of capture. The study was set up to simulate conditions that may occur during a largemouth bass tournament. Simulated tournaments were held in August, November, February, May, and July. Survival of prerelease and postrelease fish was higher when water temperatures were cool during fall and winter. Survival of largemouth bass released within 30 min was 98.9%, which was higher (P < 0.01) than survival of fish held in live wells without a water conditioner (90.8%). Fish held for 3–9 h in live wells with a water conditioner had a 96.5% survival, which was higher (P < 0.05) than survival for those held in unconditioned water. Largemouth bass caught in July had higher mortality than fish caught in November, February, or May. Indications are that addition of a water conditioner to live wells enhances surviv...

Survival of Caught and Released Largemouth Bass after Containment in Live Wells

Total protein in plasma and muscle of grass carp Ctenopharyngodon idella was significantly lower (P < 0.05) in fish exposed to 53.0 mg diquat/L than in fish exposed to 2.0 mg diquat/L. Generally, total protein in fish exposed to 2.0 mg diquat/L was not significantly different from total protein in control fish (0.0 mg diquat/L) throughout 168 h of exposure. Aspartate aminotransferase (=glutamic-oxaloacetic transaminase; GOT) activities increased significantly in plasma, muscle, and liver of fish exposed to 53.0 mg diquat/L. However, in fish exposed to 2.0 mg diquat/L, plasma and liver GOT decreased significantly. Alanine aminotransferase (=glutamicpyruvic transaminase; GPT) activities increased significantly in plasma and liver of fish exposed to 53.0 mg diquat/L, whereas there was no change in fish exposed to 2.0 mg diquat/L.

Wilmer A. Rogers

Papers

Anatomy and histology of the channel catfish

Chemiluminescence by peripheral blood phagocytes from channel catfish: Function of opson in and temperature

Edwardsiella ictaluri from walking catfish, Clarias batrachus L., in Thailand

Survival of Caught and Released Largemouth Bass after Containment in Live Wells

Changes in Total Protein and Transaminase Activities of Grass Carp Exposed to Diquat