Egg Production of Gulf Killifish Is Dependent on Broodstock Rearing Density but Not Spawning Substrate Surface Area

Abstract

The Gulf Killifish Fundulus grandis is a popular baitfish for recreational fisheries and is a candidate for commercial‐scale culture; however, its relatively low fecundity compared to other baitfish presents a production challenge. Egg output in relation to broodstock densities and spawning mat surface areas was evaluated in recirculating aquaculture systems (RASs). In experiment 1, broodstock were stocked at two densities (45 and 90 fish/m³), with eggs collected three times per week for 8 weeks. Broodstock (15–17 g) that were held at 45 fish/m³ had greater reproductive output (3.93 eggs·female−1·d−1) than broodstock that were held at 90 fish/m³ (2.22 eggs·female−1·d−1). However, there was no difference between the number of eggs per collection (1,005 and 1,107 eggs per 3,600‐L tank) or total egg production (23,202 and 25,802 eggs per 3,600‐L tank), indicating that reproductive output was limited by another factor, such as available spawning substrate. Therefore, in experiment 2, broodstock (12–16 g) were stocked at a density of 100 fish/m³ in all tanks and were held for 8 weeks with one of three spawning mat (Spawntex) surface areas: 4,500 cm2 (one tier), 9,000 cm2 (two tiers), or 13,500 cm2 (three tiers). Reproductive output was 2.12, 2.27, and 2.21 eggs·female−1·d−1 for the one‐tier, two‐tier, and three‐tier treatments, respectively, with no differences among treatments. There was also no among‐treatment difference in the number of eggs per collection (1,724, 1,858, and 1,794 eggs/tank) or in the total number of eggs collected (27,587, 29,728, and 28,704 eggs/tank), suggesting that increasing the surface area of spawning material does not increase egg production. Therefore, a stocking density of 45 fish/m³ and a spawning mat surface area of 4,500 cm2 in commercial‐scale RAS broodstock tanks result in similar egg production compared to a higher stocking density and greater spawning mat surface area.

Plasticity, repeatability, and phenotypic correlations of aerobic metabolic traits in a small estuarine fish

“…The lack of sex effects in this study might be attributed to the age of the fish used, which were probably young-of-the-year (Greeley and MacGregor, 1983) and not reproductively active at the time of capture. In addition, fish in the current study were held at relatively high density (∼60 fish per m 3 ), which has been shown to reduce egg production in F. grandis (Chesser et al, 2019). However, over the course of laboratory maintenance, fish grew significantly and developed dimorphic coloration typical of sexually mature individuals of this species.…”

Plasticity, repeatability, and phenotypic correlations of aerobic metabolic traits in a small estuarine fish

“…The lack of sex effects in this study 568 might be attributed to the age of the fish used, which were probably young-of-the-year (Greeley 569 and McGregor, 1983) and not reproductively active at the time of capture. In addition, fish in the 570 current study were held at relatively high densities (~60 fish per m 3 ), which have been shown to 571 reduce egg production in F. grandis (Chesser et al, 2019). On the other hand, over the course of 572 laboratory maintenance, fish grew significantly and developed dimorphic coloration typical for 573 sexually mature individuals of this species.…”

Spawning habits and embryonic development of the lampeye killifish Aplocheilichthys spilauchen in ex situ fresh-and-brackish water environments

“…Premised on previous ndings that the species is a continuous substrate spawner with low fecundity (Okyere, 2012), this experiment (1) assessed the spawning potential, (2) investigated whether the killi sh has preference for the colour of its spawning substrate, (3) monitored the stages of embryonic development, and 4monitored the sizes of embryos and duration of embryonic development, in ex situ fresh-and-brackish water environments. With the growing interests in using killi sh for a multiplicity of purposes including breeding for bait sh (Chesser et al, 2019) and as tool for embryology education (Genade, 2016), the usefulness this study may possibly traverse biocontrol to other facets killi sh utility.…”