Modeling the impact of climate variability on Black Sea anchovy recruitment and production

Abstract

The connection of climate variability with anchovy spawning and recruitment in the Black Sea in particular, and other ecosystems in general, was studied using a two-way coupled lower trophic level and anchovy bioenergetics model. Climate variability was represented by a 50-yr time series of daily temperature and vertical mixing rates with stochastic variations. Temperature was found to be the dominant factor influencing early life stages and hence population dynamics of Black Sea anchovy as marked by a high correlation of anchovy egg production and recruitment success in response to changes in temperature. Each decrease of 2°C in summer mean temperatures resulted in a delay in the timing of egg production of between 12 and 19 days. Water temperatures in the spawning season had a greater influence than the number of available spawning females on the intensity of egg production. Anchovy recruitment was similarly influenced by temperature, with decreased temperatures resulting in a significant delay in the onset of peak recruitment during the fall by 21-38 days. Also, recruitment numbers in December decreased by about 20% with decreasing temperatures. The impact of temperature on production was slightly diminished by the impact of vertical mixing. The strong linkage of climate variability with anchovy spawning and recruitment has an important prediction potential for short-term anchovy stock estimations, which may serve fisheries management purposes.

Climate, Anchovy, and Sardine

“…Ocean temperature has been shown to be important to explain fluctuations in anchovy and sardine in the North Pacific (Chavez et al 2003, Jacobson et al 2005, Lindegren et al 2013), the Humboldt Current System (Alheit & Niquen 2004), and the Black Sea (Guraslan et al 2014). Pacific sardine production was more closely related to upwelling caused by wind-stress curl than to coastal wind stress (Rykaczewski & Checkley 2008).…”

Understanding the Impact of Environmental Variability on Anchovy Overwintering Migration in the Black Sea and its Implications for the Fishing Industry

“…Gucu et al (2016) already suggest the existence of local, nonmigrating anchovy populations in the southern Black Sea basin, an area that was previously thought less suitable for spawning. However, the response of fish populations to continued warming is rather complex and non-linear (Guraslan et al, 2014), as anchovy metabolism, spawning and recruitment success are temperature dependent.…”

“…As anchovy is a fast-growing and short-lived species, the influence of environmental drivers may regulate survival rate of the early life stages (Guraslan et al, 2014;Gucu et al, 2016). Of these factors, eutrophication, climate variability (Oguz et al, 2008a,b) and the invasion of an alien ctenophore (Mnemiopsis leidyi) have been stated to be of crucial influence.…”

Evolution of Future Black Sea Fish Stocks under Changing Environmental and Climatic Conditions

“…Process-based target species models such as Individual Based Models (IBMs) (e.g., Werner et al, 2001;Paris et al, 2007), bioenergetics models (e.g., Guraslan et al, 2014), Dynamic Energy Budget (DEB) models (Kooijman, 1986(Kooijman, , 2000 simulate the dynamics of e.g., feeding, growth, and metabolism, during some or all life stages of a species, sometimes also tracking transport of eggs, larvae, and individuals as a function of hydrodynamic and environmental conditions. Similar to the aforementioned statistical approaches, these tools only address a restricted number of the processes linked to production and are rarely tested against the actual reproductive and growthrelated dynamics of stocks.…”