Bonga shad (Ethmalosa fimbriata) spawning tactics in an upwelling environment

• Published in: Fisheries oceanography Vol. 28; no. 6; pp. 686 - 697
• Main Authors: Baldé, Bocar Sabaly, Döring, Julian, Ekau, Werner, Diouf, Malick, Brehmer, Patrice
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell Publishing Ltd 01.11.2019; Wiley
• Subjects: Abiotic factors; Biodiversity and Ecology; Biology; climate; Climate change; clupeid; data‐poor fisheries; Economics; Eggs; Environmental conditions; Environmental Sciences; Ethmalosa fimbriata; Fecundity; Fish; Fish eggs; Fish populations; Fisheries; Fisheries management; Fishery management; Fishing; Fluctuations; Food availability; Food supply; Freshwater fishes; Ocean circulation; oceanography; optimal environmental window; Pelagic fish; Pelagic fisheries; Populations; Recruitment; Recruitment (fisheries); reproductive adaptation; salinity; Sea surface; Sea surface temperature; small pelagic fish; socioeconomics; Spawning; surface water temperature; Tactics; Upwelling; Virtual population analysis; Water temperature; Winds; clupeid; data-poor fisheries; ACL; variability; cycle; stocks; sardinella-aurita; fecundity; small pelagic fish; dynamics; recruitment; reproductive adaptation; optimal environmental window; energetics; climate change
• DOI: 10.1111/fog.12451
• ISSN: 1054-6006

Successful recruitment in small pelagic fish populations inhabiting upwelling zones is subject to variation in fecundity and is driven by spatial and temporal fluctuations in environmental conditions, that is, mainly sea surface temperature, salinity and food availability. These fluctuations in abiotic factors have stimulated small pelagic fish populations to exhibit specifically adapted spawning tactics. To better understand to what extent a short‐lived exploited fish species such as bonga shad Ethmalosa fimbriata has adapted to an upwelling environment, we have investigated the interrelationship between upwelling intensity as a proxy for productivity and population fecundity by means of a virtual population analysis. We found that females of intermediate size contributed significantly more eggs to the population's fecundity than smaller or larger ones. Our model results further indicate that E. fimbriata exhibits a spawning preference at water temperatures of around 25°C and upwelling intensities of around 2.5 m3 s−1 m−1. Hence, we hypothesize that climate change‐driven increases in sea temperatures and modifications of upwelling‐favourable winds could significantly impact the species’ reproductive biology. To understand how climate change might impact fisheries, spawning tactics of small pelagic fishes are important to assess as well as their recruitment success. Such information is particularly relevant in countries where the fishery is critical at socio‐economic level, to better implement fisheries management addressing multiple stressors.