Reproductive strategies and seasonal changes in the somatic indices of seven small-bodied fishes in Atlantic Canada in relation to study design for environmental effects monitoring

Abstract

Small-bodied fishes are more commonly being used in environmental effects monitoring (EEM) studies. There is a lack of understanding of the biological characteristics of many small-bodied species, which hinders study designs for monitoring studies. For example, 72% of fish population surveys in Canada's EEM program for pulp and paper mills that used small-bodied fishes were conducted outside of the reproductive period of the species. This resulted in an inadequate assessment of the EEM program's primary effect endpoint (reproduction) for these studies. The present study examined seasonal changes in liver size, gonad size, and condition in seven freshwater and estuarine small-bodied fishes in Atlantic Canada. These data were used to examine differences in reproductive strategies and patterns of energy storage among species. Female gonadal recrudescence in all seven species began primarily in the 2-month period in the spring before spawning. Male gonadal development was concurrent with females in five species; however, gonadal recrudescence began in the fall in male three-spined stickleback (Gasterosteus aculeatus) and slimy sculpin (Cottus cognatus). The spawning period for each species was estimated from the decline in relative ovary size after its seasonal maximum value in spring. The duration of the spawning period reflected the reproductive strategy (single vs multiple spawning) of the species. Optimal sampling periods to assess reproductive impacts in each species were determined based on seasonal changes in ovary size and were identified to be during the prespawning period when gonads are developing and variability in relative gonad size is at a minimum.

The biology and ecology of slimy sculpin: A recipe for effective environmental monitoring

“…a Migration is less of a concern for non-point sources of contamination. In the past 15 years in Canada, much work has been done following the sentinel species approach using small-bodied species (Gibbons et al 1998;Gray et al 2005aGray et al , 2005bBarrett et al 2015). This is in contrast to much of the initial monitoring under EEM, which focused on large-bodied species .…”

“…Although many characteristics were suspected and generally true (Minns 1995), specifics were unknown. These barriers have been gradually addressed and monitoring programs using small-bodied fish have become common (Barrett et al 2015). Several characteristics inherent to many small-bodied fish make them particularly useful for monitoring studies.…”

“…Several characteristics inherent to many small-bodied fish make them particularly useful for monitoring studies. Small-bodied fish are generally found at high enough densities for collection of adequate sample sizes, many species show high site fidelity that aids in establishing exposure to environmental stressors, their short life spans relate to rapid responses to environmental changes, confounding factors such as fishing pressure are usually absent, and life history characteristics can still be easily measured, e.g., age and (or) size distributions, energy storage (liver size, condition), and energy expenditure (gonad size, reproductive output) (Minns 1995;Environment Canada 1997;Gibbons et al 1998;Gray et al 2002;Brasfield et al 2013;Arciszewski et al 2015a;Barrett et al 2015). Furthermore, there is generally less public concern about taking small-bodied "forage" fish for monitoring than charismatic sport fishes.…”

“…Of the small-bodied freshwater fish species used in monitoring (Barrett and Munkittrick 2010;Barrett et al 2015), the slimy sculpin is the leading choice for a sentinel species program in most of Canada and northern parts of the United States. They closely match the profile for an ideal sentinel species in areas where they are present in sufficient numbers.…”

Thermal Stress Induces Metabolic Responses in Juvenile Qingtian Paddy Field Carp Cyprinus carpio var qingtianensis

“…Therefore, the liver is typically used as a biological target in studies pertaining to the monitoring of the environment and studies pertaining to the stress response. Previous research studied differences in seasonal reproductive strategies and energy storage patterns among different species of freshwater fish using livers from seven species of freshwater and estuarine small fish from Atlantic Canada [ 32 ]. Recently, substantial research has been performed on how heat stress affects fish livers [ 33 , 34 , 35 , 36 ].…”