Effects of environmental factors on survival, growth, and production of American shad larvae

Abstract

Episodic increases in temperature of d5 C above 20 C, over 48 h or declines in pH of 1·0 unit from pH 7·0 reduced survival of yolk-sac and feeding-stage larvae of American shad Alosa sapidissima. Over 16 days all measures of survival, growth, and production were more favourable at each higher temperature in the 15-25 C range. More favourable responses were also obtained at the higher prey level (500 v. 50 Artemia nauplii l 1 ) and at the higher pH (7·5 v. 6·5). Combinations of high temperature and high prey levels, at pH 7·5, led to highest larval production. Little growth or production occurred at 15 C, regardless of pH or prey level. The effect of pH was strong with respect to survival, but weak with respect to growth. In attempts to restore American shad populations by larval stocking, release times and sites can be critical to optimize survival and eventual returns. Releases of larvae potentially will be most effective when made at temperatures >20 C, pH>7·0, and prey levels >50 l 1 . These conditions are most likely to occur in Maryland tributaries of Chesapeake Bay between mid-May and early June. 1999 The Fisheries Society of the British Isles

Post-release stranding rates of stocked allis shad (Alosa alosa) larvae exposed to surface wave action

“…In line with Leach and Houde (1999), our results suggest that careful choice of the release site is crucial in order to reduce losses. The results indicate that fish should be released in areas without waves, e.g.…”

“…Thus, the weather conditions should be considered if the stocking time table is flexible enough. Also Leach and Houde (1999) point out that timing of the stocking can be critical for return rate of American shad. They advise to avoid too early stocking, when water temperatures are still low, as growth and survival of American shad increases with temperature.…”

Human Impacts to River Temperature and Their Effects on Biological Processes: A Quantitative Synthesis1

“…, 2007). In contrast, for organisms that operate below the optimum, warming impacts would occur on the rising curve, possibly providing a functional benefit (Leach and Houde, 1999; Whitledge and Rabeni, 2002; Billman et al. , 2006).…”

Validation of daily increment formation and the effects of different temperatures and feeding regimes on short‐term otolith growth in Australian smelt Retropinna semoni

“…An increased metabolic rate incurred at higher temperatures is also a likely cause of the interaction effect between temperature and food on otolith growth in the present study, where the highest growth was observed in the high temperature/high food treatment. Leach & Houde (1999) also found that a combination of high temperature and high prey levels led to the highest growth rates. A higher metabolic rate may also explain why no larvae from the starved/high temperature treatment survived the full length of the trial, when compared with the starved/low temperature treatment which had a >50% survival.…”