The importance of live-feed traps - farming marine fish species

Abstract

This article analyses the challenges of different live-feed regimes for the rearing of marine finfish larvae and discusses the potential alternative live feeds to avert a future live-feed trap. Live feeds are indispensable for the successful rearing of larvae of most marine fish species. Brine shrimps (Artemia) and rotifers comprise the live feeds of choice in marine aquaculture today. However, their nutritional composition is deficient in especially essential fatty acids, and enrichment with fish oil is needed. Fish oil is considered a limited resource owing to its origin in fully exploited wild fish stocks. Moreover, fluctuations of the natural population of Artemia will, most likely, influence future availability and prices. This emphasizes the need for optimal exploitation of available live-feed resources and development of new sustainable alternatives, such as copepods. An array of solutions to these problems are presented to avoid a future live-feed trap and to reduce dependence on limited resources that influence future production possibilities, species diversification, price volatility and productivity in the aquaculture sector.

Cultivation success and fatty acid composition of the tropical copepods Apocyclops royi and Pseudodiaptomus annandalei fed on monospecific diets with varying PUFA profiles

“…The two copepods have a high tolerance to temperature, salinity, hypoxia, etc. (Blanda et al., 2015; Pan et al., 2016), and does not require high‐quality diets or enrichment, effectively avoiding the so‐called ‘fish oil trap’ ( sensu Nielsen et al., 2017). Furthermore, their relatively fast generation time and, especially with regards to A. royi, high‐density tolerance (P. M. Jepsen et al, unpubl.)…”

“…Numerous studies point towards copepods as the ultimate live feed product mimicking nature's choice for fish larvae in marine pelagic food webs (Shields et al., 1999; Toledo et al., 1999; Wilcox et al., 2006). Often, when discussing production of copepods as live feed, the topic of resting eggs from calanoids belonging to the superfamily Centropagoidae arises (Abate et al., 2015; Marcus & Murray, 2001; Nielsen et al., 2017). It has been stated that to successfully apply copepods in aquaculture, they must be a shippable product in league with rotifers and Artemia cysts (Nielsen et al., 2017).…”

“…However, rotifers and Artemia are more popular choices as first feed due to the organisms already established use in aquaculture and their simplistic culturing methods. Rotifers can be cultured on the cheap and low‐nutritious baker's yeast (Conceição et al., 2010; Dhert et al., 2014; Eryalcin, 2018, 2019) and ~50% of Artemia cysts are obtained directly from hypersaline ponds where they occur naturally (Lavens & Sorgeloos, 2000; Nielsen et al., 2017). However, both rotifers and Artemia lack specific EFAs and need enrichment by fish oil emulsions to meet the dietary requirements of fish larvae (Dhert et al., 2001, 2014; Eryalcin, 2018; Sorgeloos et al., 2001).…”

Molecular physiology of copepods - from biomarkers to transcriptomes and back again

“…On the other hand, cultured free-living copepods can have significant benefits for aquaculture. Relative to more traditional food sources like brine shrimp and rotifers, copepod nauplii can result in increased survival and other quality metrics of fish larvae (Drillet et al, 2011;Nielsen et al, 2017). However, rearing copepods at high densities on a commercial scale requires optimization and is a subject of active research (Nilsson et al, 2017 and references therein;Vu et al, 2017).…”

Copepod Embryonic Dormancy: “An Egg Is Not Just an Egg”

“…Rearing marine finfish other than salmonids often requires live feed for their larval stages, and here copepods are the optimal solution (Conceicão et al, 2010;Rasdi and Qin, 2014;Nielsen et al, 2017). Copepods have the right size, behavior, and biochemical profile to sustain fish larvae; and they enable far better survival, reduce outbreaks of abnormalities, and maintain original wild-type pigmentation, all crucial for the fastest-growing food industry on Earth-aquaculture (Drillet et al, 2011a).…”