Fecundity regulation in horse mackerel

Abstract

Egg production methods have been used successfully in the provision of advice for fisheries management. These methods need accurate and unbiased estimates of fecundity. We explore the reproductive strategy of horse mackerel and estimation of fecundity. Fecundity and fecundity regulation in relation to condition was investigated over a number of years. Fulton's K, lipid content, and hepatosomatic index increased after the start of spawning, though decreased again at the end of spawning. The increase in the gonadosomatic index, fecundity, and body condition after the onset of spawning suggests that horse mackerel utilizes food resources during the spawning season and might be an income breeder. However, the decline in K and lipid before the spawning season suggests that the first batch of oocytes is developed on stored energy. Fecundity varied between years and within a spawning season. Over latitude, variations in fecundity were small. K and lipid content are not reliable indices as proxy for fecundity. Batch fecundity appears to be heterogeneous across the spawning season but homogeneous across latitude. The homogeneity of batch fecundity over latitude could indicate that the daily egg production method is an appropriate approach for estimating the abundance of a wide ranging species, as horse mackerel.

Linking the dynamic organization of the ovary with spawning dynamics in pelagic fishes

“…The present study covers the dynamics of secondary growth and primary growth oocytes; however, the recruitment from oogonia to primary growth oocytes needs to be further explored (Grier et al 2009;Thomé et al 2012;Wildner et al 2013;dos Santos Schmidt et al 2017). In addition, the thermal habitat, the distribution, and other factors such as the availability of food and specificities in breeding behaviour should also be considered to obtain an overall view of fecundity regulation in fishes (Kjesbu and Witthames 2007;Ganias 2013;van Damme et al 2014).…”

Balanced harvest: concept, policies, evidence, and management implications

“…The fundamental differences between small-scale fisheries in the developing world and the large-scale economic fisheries in the developed world ) are indicative of the potential for, and the constraints to, implementing balanced harvest. Modern economy, selective consumers, selective fisheries, variable harvesting costs, and the conventional management paradigm are strong obstacles for balanced harvest as reflected in the lack of empirical examples, and the problematic implementation (Charles et al 2016;Garcia et al 2016b;Howell et al 2016;Reid et al 2016). On the other hand, where food production is the primary motivation, then fishing patterns sharing some of the characteristics of balanced harvest have arisen naturally and proved stable and successful without the need for complex management.…”

“…(1) As a strategic guidance. Like EAF, into which it fits, balanced harvest provides a strategic direction (a ''compass'') for better aligning fisheries with UNCLOS and the CBD (Zhou et al 2015;Charles et al 2016;Garcia et al 2016b;Howell et al 2016;Reid et al 2016). For example, managing commercial species and bycatch species by different policies with contrasting objectives (e.g.…”

Preovulatory follicle growth dynamics indicates daily spawning synchronicity in wild-caught Atlantic horse mackerel off Portugal

“…The Atlantic horse mackerel, Trachurus trachurus, is a commercially important species, whose biomass has been estimated applying the egg production methods for almost 30 years (Gordo et al, 2008;Van Damme et al, 2014). Since 2007 the DEPM is being applied to the southern stock (ICES, 2008(ICES, , 2012(ICES, , 2017Gonçalves et al, 2009).…”