Mortality of Lingcod, Ophiodon elongatus, Related to Capture by Hook and Line

Lingcod, Ophiodon elongatus, were captured by hook and line (sport rod and reel gear and commercial troll gear) at two coastal California locations and held in aquaria for periods of up to 32 days for evaluation of capture-related mortality. Three of 69 lingcod captured with rod and reel gear died of capture-related injuries (4.3% mortality; 95% confidence interval 0–9.3%). None of 15 lingcod captured with troll gear died of capture-related injuries. Due to the low overall mortality rate, there were no discernable trends in mortality with respect to sex, length, depth of capture, and terminal tackle (bait vs. lure). Of 38 fish with visible hooking wounds, 26 showed evidence of wound healing during the holding period.

Size-related Hooking Mortality of Incidentally Caught Chinook Salmon, Oncorhynchus tshawytscha

Mortality associated with the incidental catch and release by commercial trollers of two size classes of chinook salmon, Oncorhynchus tshawytscha, was assessed. Observed cumulative mortality 4-6 days after hooking was 18.3 percent for sublegal-sizefish « 66 cm FL) and 19.0 percent for legal-sizefish. Size of fish was not significantly related to mortality; however, when the results were combined with data from a previous experiment, there was a significant inverse relationship between fish length and mortality. Hooking mortality estimates calculated from tagging experiments and observed relative mortality of legal-and sublegal-size fish held in net pens, were used to derive a range for total hooking mortality of 22.0-26.4 percent for sublegal-size chinook salmon and 18.5-26.4 percent for legal-size chinook salmon.

Electrofishing in streams that dry up in the 50's

Three men electrofishing in an unknown a dry stream in North West England, UK, in the 50's. This photo is part of a Photo Album that includes pictures from 1935 to 1954.