Reproductive characteristics of the fishery important temperate demersal berycid Centroberyx gerrardi indicate greater reproductive output in regions of upwelling

Abstract

The reproductive biology of Centroberyx gerrardi (Günther) was investigated across ~2,000 km of its southern Australian distribution, encompassing different jurisdictions and varying environmental features. Greater gonad mass and prevalence of spawning fish, along with lower ratios of lengths at maturity:maximum lengths and ages at maturity:maximum ages, were identified at the western‐most (Capes) and eastern‐most (Great Australian Bight; GAB) regions. Across the study region, spawning peaks in summer/autumn, when water temperatures are warmest. Regional differences in potential “reproductive output,” while not consistent with the eastward decline in mean monthly water temperature, may instead be related to summer upwelling in the Capes and GAB, driving greater oceanic productivity prior to peak spawning, supporting larval survival. In autumn, the prevailing southward and eastward flowing, downwelling Leeuwin Current (LC) strengthens, providing a dispersal mechanism along the west and south Australian coasts, but limiting upwelling effects. Predicted changes in environmental conditions and their potential impacts on C. gerrardi are discussed, in particular how these factors may affect recruitment to stocks and fisheries, requiring a better understanding of source‐sink relationships for this species. As environmental changes occur, management strategies to sustain fish resources must adapt to spatially variable and changing reproductive output and be collaborative across jurisdictions.

The life history characteristics of Neosebastes pandus and the relationship between sexually dimorphic growth and reproductive strategy among Scorpaeniformes

“…The short, 3‐month, late autumn to mid‐winter spawning period exhibited by N. pandus is identical to that for Scorpis aequipinnis in southern Western Australia and overlaps with other fish species from this region such as Sillaginodes punctatus (Cuvier 1829), A. gouldii , N. valenciennesi , C. rubrolabiatus , A. georgianus and C. gerrardi (Günther 1887) (Coulson, 2019; Coulson et al ., 2009, 2010, 2012, 2019; Fairclough et al ., 2000a; Hyndes et al ., 1998). Gonadal recrudescence in N. pandus , as in S. aequipinnis and A. georgiana , is initiated when day length is declining and water temperature starts to decline (see Figure 1 in Coulson et al ., 2012).…”

“…This parallels the typical situation with temperate fish species that spawn in winter and thus when water temperatures are low (Lam, 1983). The timing of spawning by N. pandus may also be influenced by the presence of the pole‐ward flowing Leeuwin Current (LC), which is strongest in winter months and proposed to transport the eggs and larvae of other teleosts to nursery grounds in waters off the south coast of Western Australia (Coulson et al ., 2010, 2019; Fairclough et al ., 2000a).…”