The biology and ecology of tropical marine sardines and herrings in Indo-West Pacific fisheries: a review

Abstract

Tropical sardines and herrings (Family Clupeidae) form important fisheries resources in the Indo-West Pacific region. However knowledge of their biology and ecology is largely scattered across diverse localised studies. In addition, their challenging taxonomy due to numerous, morphologically similar species, coupled with data collected from dispersed, often small-scale and mixed species fisheries, creates difficulties for comparing species-level research and fisheries statistics across the region. This review considers four main groups of tropical marine clupeid species important for Indo-West Pacific fisheries—Sardinella (subg. Sardinella) species (‘Round-bodied Sardinellas’), Sardinella (subg. Clupeonia) species (‘Flat-bodied Sardinellas’), Amblygaster species (‘Tropical Pilchards’), and Herklotsichthys and Escualosa species (‘Tropical Herrings’)—and collates and synthesises existing knowledge on early life history, reproduction, trophic biology, habitat associations and population dynamics. Most research on tropical clupeid biology and ecology in the Indo-West Pacific is concentrated on the Round-bodied Sardinellas (S. longiceps and S. lemuru) from a few major fishery locations; other species-groups have been studied sporadically across their distributions. Characteristics such as maximum size, life span, size at first maturity and some habitat associations are generally similar within species-groups and differ between groups. However differences within the same reported species highlight the importance of continued work to improve taxonomic identification. There remain substantial gaps in knowledge on all species-groups. Regular critical review of specific research topics, such as reproductive parameters and population dynamics, would assist to standardise methods and terminology used, enable consolidation and comparison of findings, identify local research agenda, and help build and improve research on these important tropical species.

Untangling Tales of Tropical Sardines: Local Knowledge From Fisheries in Timor-Leste

“…Based on lengths at first maturity reported elsewhere in the IWP (Hunnam, 2021), these probably refer to juveniles and adults respectively. Both small and large specimens collected were identified as S. gibbosa, however we suspect landings of this group in Timor-Leste comprise at least two taxonomic species.…”

“…Small specimens only noted from some north-coast fisheries (but may reflect research effort). Large fish (caught in 1.25 mesh) are probably adults, while small fish (1 mesh) are probably juveniles -based on commonly reported standard length at first maturity for S. gibbosa, ∼11 cm (Hunnam, 2021). Seasonally abundant in coastal fishing grounds (<5 km from shore).…”

“…Oily flesh. (Hunnam, 2021). Small specimens were not mentioned at any sites -juvenile S. lemuru may not be present in Timor-Leste's nearshore waters, or may not be distinguished (or distinguishable) from other small sardines caught.…”

“…Fishers only distinguished large specimens, caught in 1.25 (32 mm) or 1.5 (38 mm) mesh. Based on lengths at first maturity reported elsewhere in the IWP (Hunnam, 2021), these are probably adults. Juvenile S. lemuru may not be present in Timor-Leste's nearshore waters, or may not be distinguishable from other small sardines caught.…”

“…These fisheries provide livelihoods for hundreds of thousands of fishers and post-harvest workers (e.g., Kripa et al, 2018;Rola et al, 2018) and an affordable source of protein and micronutrients for human consumption (e.g., Roeger et al, 2016;Rola et al, 2018). While tropical marine clupeids share some attributes -short life-spans (generally ranging from 1 to 4 years), typically reach maturity by 12 months, occupy low trophic levels and occur in continental shelf waters -species differ in maximum size, size at maturity, habitat preferences, seasonal or life-cycle migration patterns and response to climateocean variation (reviewed in Hunnam, 2021). Information on the composition of mixed-species fisheries and species' biology and ecology is therefore important for effective fisheries monitoring, management and sustainability.…”