Increasing Coastal and Continental Shelf Water Temperatures Influence the Start of the Glass Eel Fishery and Recruitment Abundance for American Eels in Atlantic Coastal Nova Scotia

Abstract

AbstractThe effect on fish life history of warming oceanic water temperatures is a modern concern. Warming coastal and continental shelf sea surface temperatures (SSTs) were examined for their effect on the arrival of American Eel Anguilla rostrata glass eels to coastal waters as represented by the start of commercial elver fisheries along the Atlantic coast of Nova Scotia, Canada. Elver fishery start dates were significantly earlier for a group of three rivers along the coast southwest of centrally located Halifax and for a northeastern group of two rivers. Between 1996 and 2020, fishery start dates became earlier by about 26 d for the southwestern river group and by about 34 d for the northeastern group. Progressively earlier starts to elver runs and associated commercial fisheries have implications for fisheries management when fixed fishing seasons become mismatched with run timing. Coastal and continental shelf SSTs were significantly higher for the southwestern river group than for the northeastern river group. Fishery start dates were significantly correlated with coastal and continental shelf SSTs only for the southwestern river group and not for the northeastern river group. The annual elver index for the East River, Chester, increased significantly between 1996 and 2018 and was significantly correlated with coastal and continental shelf SSTs, suggesting that increasing oceanic water temperatures influence glass eel recruitment. Elver relative condition had no significant effect on elver recruitment and was not affected by continental shelf SSTs.