Protracted Reproduction in Sunfish: The Temporal Dimension in Fish Recruitment Revisited

Abstract

Abstract. Understanding how life histories influence reproductive success under uncertain conditions is necessary to predict population dynamics. For many organisms, protracted reproduction may increase expected offspring recruitment in variable environments, requiring that temporal patterns of reproduction be considered when developing management or conservation strategies. We explored the interrelationships among birth date, production of embryos on nests, survival of larvae to the open-water stage, and survival of juveniles through the first fall and winter of life for bluegill and pumpkinseed sunfish (Lepomis macrochirus and L. gibbosus) in Lake Opinicon, Ontario, during May 1998 through May 1999. Age-0 sunfish were sampled with nesting surveys for embryos, surface tows for free-swimming larvae, and seining/trawling for juveniles. Age of juveniles (days post swim-up) was quantified using otoliths. The abundance of embryos on nests and the density of open-water larvae were unrelated across all dates and sites. Although 40% of larvae had appeared in the open water by 12 June, most juveniles sampled in the fall were produced after that time, suggesting that high mortality of early produced larvae occurred. Larval survival to the juvenile stage was generally unrelated to the abundance of edible zooplankton taxa during swim-up from nests. Larval survival was often highest at temperatures Ͼ23.5ЊC. Fall length of age-0 sunfish increased with increasing age. Both agespecific length and mean lengths shifted positively between October 1998 and May 1999, suggesting that growth of all individuals and perhaps selective mortality of small juveniles occurred.Although early reproduction may increase sizes reached by fall and thereby improve overwinter survival, early hatched larvae are subject to variable environmental factors that may reduce survival. Late-hatched larvae may reach relatively smaller sizes by fall, but have higher survival probabilities during this life stage. Protracted reproduction appears to be a response to variable environmental factors influencing growth and survival across multiple life stages. As such, all reproducing adults, rather than those perceived to produce offspring during typically favorable times, must be protected from exploitation or other human-induced perturbations.

The effects of cool and variable temperatures on the hatch date, growth and overwinter mortality of a warmwater fish in small coastal embayments of Lake Ontario

“…One person counted the number of daily rings on each otolith three times under oil immersion using a compound light microscope, and the readings were averaged to obtain an age in days. Since it takes at least three days for pumpkinseed eggs to hatch (Scott and Crossman, 1998) and daily rings are not deposited on otoliths for at least 24 hours after hatching (Garvey et al, 2002), we added seven to the average daily ring count to ensure that estimated ages were biased slightly older than actual ages. The capture date, location and length of the pumpkinseed were not revealed to the reader.…”

“…We used DataThief III (Tummers, 2006) to recover data coordinates from published graphs of pumpkinseed nest densities. Nest densities were obtained from six different lakes in the Ontario Ministry of Natural Resources' Kawartha Lakes or eastern Ontario Districts: Little Round Lake, Warrens Lake, Black Lake, Beloporine Lake, Lake Opinicon and Duncan Lake (Danylchuk and Fox, 1994;Garvey et al, 2002). Data from all lakes were available for 1992 and additional data for 1998 were available from Lake Opinicon.…”

“…For warmwater centrarchids, spawning begins when a threshold temperature is reached; thresholds for various species range from 12 to 22°C (Burns, 1976;Danylchuk and Fox, 1994;DeVries et al, 2009;Mittelbach and Persson, 1998). Earlier-hatched fish usually contribute disproportionately to recruitment because they are able to grow for longer periods of time during their first summer, increasing their size and, therefore, overwinter survivorship (Ludsin and DeVries, 1997;Miller and Storck, 1982), but there are exceptions (Garvey et al, 2002;Santucci and Wahl, 2003).…”

Spawning period of Mediterranean marine fishes

“…The onset and duration of fish spawning have long been central issues in fisheries biology, ecology and management (Holt and Byrne 1898) because of their importance on recruitment (Beaugrand et al 2003), survival (Garvey et al 2002), and stock biomass, and thus fishery yield (Kjesbu and Witthames 2007). However, the examination of the onset and duration of spawning across or within taxonomic groups is rather rare in fish reproductive biology (Slastenenko 1956;Grubišić 1962;Kock and Kellermann 1991;Murua and Saborido-Rey 2003) and so is a holistic approach on reproduction across taxa or areas (Beverton 1963(Beverton , 1992Abaunza et al 2003).…”

Biotic and Abiotic Influences on Nest-hatching Outcome in the Japanese Fluvial Sculpin, Cottus pollux

“…For nest-holding fishes, unpredictable floods in the breeding season may cause accidental loss of nests and fertilized eggs (Noltie & Keenleyside 1987, Lugli et al 1992, Mori 1995. Understanding the relationships among the timing of reproduction, physical characteristics of nests, and hatching outcome of nestholding fishes in variable environments is a crucial requisite for their conservation and management (Garvey et al 2002).…”