Population ecological parameters and biomass of anchovy kilka Clupeonella engrauliformis in the Caspian Sea

Abstract

Through most of the last century, three endemic kilka species supported major commercial species in the Caspian Sea. It is clear that catches and abundance of all species have changed, but catch and sampling data are limited and stock assessments are inadequate. Recent changes in the Caspian Sea ecosystem have occurred as a consequence of climatic environmental change (sea level change) and ecologic change caused by the invasive ctenophore Mnemiopsis leidyi. This paper examines the effects of these changes on the population biology and biomass of anchovy kilka Clupeonella engrauliformis in Iranian waters of the Caspian Sea from 1995 to 2004. For most years during this 10-year period, we estimated the age structure of catch, length-weight relationship, von Bertalanffy growth parameters, condition factors, sex ratios, maturity stages determined from ovarian analysis, natural and fishing mortality, age at first capture, and spawning biomass. The instantaneous coefficient of natural mortality was estimated as 0.473/year and the instantaneous coefficient of fishing mortality varied during the 10-year period between 0.541 and 2.690/year. Biomass of anchovy kilka declined from about 186 000 t in 1996 to less than 12 000 t in 2004. Recent high fishing rates were not sustainable after the introduction of Mnemiopsis, so overfishing is part of the explanation for the collapse of anchovy kilka in the Caspian Sea.

Changes in biodiversity of phytoplankton, zooplankton, fishes and macrobenthos in the Southern Caspian Sea after the invasion of the ctenophore Mnemiopsis Leidyi

“…High fishing rates of the main pelagic zooplanktivorous fish, kilka Clupeonella spp., especially during 1998-2000, were not sustainable after the invasion of M. leidyi in the southern Caspian Sea (Fazli and Roohi 2002;Fazli et al 2007). The introduction of M. leidyi resulted in a reduced abundance and biomass of zooplankton, the main food source of kilka.…”

“…The collapse of the kilka fishery has damaged the local and regional economy, and the social conditions of the fishermen (Bilio 2004). Total biomass of the anchovy kilka catch, which used to make up 80-90% of total kilka catch (bigeye kilka, common kilka and anchovy kilka) (Fazli and Besharat 1998), declined from *186,000 t in 1996 to 12,000 t in 2004 in Iranian waters (Fazli et al 2007). After the invasion of this ctenophore, both abundance and species number of edible zooplankton also changed (Roohi et al 2008a).…”

Antioxidant activity of protein hydrolysates from whole anchovy sprat (Clupeonella engrauliformis) prepared using endogenous enzymes and commercial proteases

“…All kilka inhabit the coastal zone to about 70 m. These three kilka species are caught in commercial fisheries by attracting them with underwater electric lights and recovering them with fish pumps. Anchovy sprat accounts for approximately 80–90% of the total kilka caught in the Caspian Sea . Kilka fishing is an important source of income and protein for fishermen in Iran, where these fish are harvested for fish oil, fish meal and fish sauce production or directly as human food.…”

“…A recent collapse of kilka fisheries has adversely affected the regional economy and nutritional status of local peoples through the loss of this protein resource. Anchovy sprat biomass declined from about 186 000 t in 1996 to less than 12 000 t in 2004 . Therefore finding an alternative way to produce higher‐quality value‐added products that fulfil market demands, increase utilisation and hopefully increase the value of each harvested fish is important.…”

Length-weight and length-length relationships of three Clupeonella species (Clupeidae) from the Caspian Sea

“…For the family Clupeidae in the Caspian Sea, there are a few LWR and LLR studies (Fazli et al, 2007;Ghotbi Jokandan, Alavi-Yeganeh, & Jamshidi, 2015;Janbaz et al, 2012;Mamedov, 2006), but there are no previous reports for length-weight or length-length relationships of the Caspian tyulka, Clupeonella caspia (Froese & Pauly, 2016).…”