The influence of oxygen minimum zone and oceanographic parameters on the length distribution of five fish species in the Arabian Sea

Issam Humaid Al-Rasady*, Jessica J. Meeuwig, Michel R. Claereboudt

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Environmental conditions strongly influence fish growth and size. Temperature, salinity and oxygen can have negative effects on growth and size when species' tolerances are exceeded. Climate modelling predicts that persistent oxygen minimum zones (OMZs), where dissolved oxygen concentration is less than 0.5 mll-1, will expand globally, in addition to increases in ocean temperature. The persistent oxygen minimum zone in a warming Arabian Sea is one of only three in the world and, as such, provides a window into the potential responses of fish fauna to decreasing oxygen levels in the global seas. Fork lengths for 19,633 fish of five economically important species (Argyrops spinifer, Drepane longimana, Epinephelus diacanthus, Lethrinus nebulosus and Pomadasys commersonnii) were measured in four regions, during four seasons and at four depth strata in the Arabian Sea in order to test the influence of these factors, as proxies for the OMZ, on mean length and length-frequency distributions. The five species showed three general responses. The first group includes E. diacanthus and P. commersonnii which were largest in the south, largest during the Northeast Monsoon and did not vary in size with depth, possibly taking advantage of rich food sources for recruits but with southern populations associated with the OMZ comprised of larger individuals. The second group was comprised of D. longimana and L. nebulosus which were smaller in shallow depths and showed no influence of region or season and appear relatively insensitive to the OMZ. These two species show typical distribution in relation to depth, with larger individuals found in deeper waters. Finally, A. spinifer, was smallest in the south and in deep waters but showed no effect of season. This may indicate a sensitivity to the OMZ where larger individuals are neither found in the south nor at depth. The results of kernel density estimates largely mirrored these results. The environmental variables were significant but explained little of the deviance in fork length, with the exception of temperature which explained approximately 40% and 26.9% of the variation in length of E. diacanthus and A. spinifer, respectively. These groupings may reflect differential species sensitivities to the OMZ which is strongest in the southern regions during the SW Monsoon. This highlights the need for careful consideration of responses to expanding OMZs, particularly with how this translates into fisheries productivity.

اللغة الأصليةEnglish
عنوان منشور المضيفThe Arabian Seas
العنوان الفرعي لمنشور المضيفBiodiversity, Environmental Challenges and Conservation Measures
ناشرSpringer International Publishing
عدد الصفحات14
رقم المعيار الدولي للكتب (الإلكتروني)9783030515065
رقم المعيار الدولي للكتب (المطبوع)9783030515058
المعرِّفات الرقمية للأشياء
حالة النشرPublished - مايو 1 2021

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