Seasonal variation in fecundity, egg case viability, gestation, and neonate size for little skates, Leucoraja erinacea, in the Gulf of Maine

Abstract

Landings of the little skate, Leucoraja erinacea, within the territorial waters of the United States are currently regulated by a federal fishery management plan (FMP). For a FMP to be effective, thorough knowledge of a species' reproductive biology is essential. Currently, little information exists on annual fecundity, egg case viability, gestation length, and neonate total length, for the little skate in the Gulf of Maine. To study these reproductive parameters, mature skates and egg cases were housed in fiberglass tanks with an open seawater system that provided natural, seasonal fluctuations in water temperature. Egg case deposition was highest during summer months with a seasonal peak in June. Of the 324 egg cases laid by seven females (c. 46 eggs per year, per female), 74.1% were viable. Gestation lengths ranged from 22 to 54 weeks throughout the four seasons. Egg cases laid in the fall had the longest gestation times (44.9 weeks,±0.13 weeks) and those laid in the spring had the shortest gestation times (24.5 weeks,±0.21 weeks). Total lengths of neonates from spring oviposition were statistically the longest (10.74±0.05 cm) when compared to neonates from other seasons; however, egg viability was statistically the lowest for spring when compared seasonally.

Intraspecific variation in physiological performance of a benthic elasmobranch challenged by ocean acidification and warming

“…In addition, another coping mechanism could involve a shift in phenology, particularly for reproduction, to adjust to warmer temperatures (Gardner et al, 2011). However, L. erinacea has a long embryonic stage and lays eggs year-round, so temperature is not a strong factor in determining reproductive timing and behavior (Palm et al, 2011).…”

“…Temperature treatments (15, 18, 20°C) were chosen to test the performance at present and projected temperatures by the end of the century IPCC, 2013;Palm et al, 2011). Each tank (150 l) was supplied with clean artificial seawater (Instant Ocean and deionized water) and had completely independent filtration, temperature and CO 2 control (i.e.…”

Higher temperatures increase developmental rate & reduce body size at hatching in the small‐eyed skate Raja microocellata: implications for exploitation of an elasmobranch in warming seas

“…Large‐scale movements of elasmobranch populations throughout their life‐cycle are often correlated with temperature ( i.e ., thermotaxis; Di Santo & Bennett, ; Economakis & Lobel, ; Hight & Lowe, ; Hunter et al, ; Matern et al, ; Vaudo & Lowe, ; Wallman & Bennett, ), which is not unsurprising given the influence of temperature on many biological processes in fishes (Magnuson et al, ; Magnuson & Destasio, ). However, one life‐stage of elasmobranchs incapable of thermotaxis is the eggs from oviparous species, which generally require a prolonged, sessile developmental period (Luer & Gilbert, ; Palm et al, ). And although increasing temperature is suspected of reducing survival of elasmobranch embryos, this has rarely been tested (Di Santo, ; Palm et al, ).…”

Adaptive phenotypic response to climate enabled by epigenetics in a K-strategy species, the fish Leucoraja ocellata (Rajidae)

“…These may both represent adaptive epigenetic responses to stressful conditions such as hypoxia in warmer waters. A previous study observed significant effects of temperature change on reproductive life-history traits in the closely related, little skate ( L. erinacea ) [24], suggestive of temperature-related epigenetic regulation also in this species. Finally, we saw high upregulation of transcripts associated with the determination of adult lifespan (figure 3 b ), and slight downregulation of those associated with ageing (figure 5 b ).…”

“…The effect of temperature on skate biology is poorly understood; however, from the few studies available, temperature may be important in determining the timing of growth patterns [23] and variation in reproductive life-history traits [24]. Previous studies have shown that winter skate in the southern Gulf of St Lawrence (sGSL) population appear to be an undescribed endemic, which are substantially divergent from the Scotian Shelf population in morphology (e.g.…”