Effects of Feed Species and HUFA Composition on Survival and Growth of the Longsnout Seahorse (Hippocampus reidi)

Abstract

Globally, wild seahorse populations are threatened due to, habitat destruction and unsustainable human exploitation among others. Furthermore, aquaculture-based mass-scale rearing is still uncommon due to the low survival rates of seahorse juveniles and exceptionally high feed costs. Previous studies have demonstrated the importance of both highly unsaturated fatty acid (HUFA) supplies and a copepod-based rearing for seahorse survival and growth. As the latter is expensive, the question arises as to how high survival rates of seahorse juveniles can be assured under low-to moderate-cost feed regimes. In particular, it remains unknown whether the diet species or their dietary HUFA profiles determine the successful development of seahorse fry. Therefore, the aims of this study were to assess the dependence of growth and survival rates of Hippocampus reidi brood on the animal feed and to infer the impact of feed species vs. dietary HUFA profiles on juvenile growth. A nutrition experiment was conducted where juveniles were treated either with enriched Artemia nauplii (low-cost diet Art) or with a mixed diet of Artemia and copepods (moderate-cost diet Art/Cop). Larval survival and growth were analyzed using Cox proportional-hazard and linear mixed-effect model analyses. We found that (i) both diets enabled good survival, (ii) diet Art/Cop resulted in superior weight and height growth, and (iii) the differential effects of diets Art/Cop and Art cannot be explained by their different HUFA compositions alone. From an economical point of view, our findings of high survival rates and relatively high growth rates with the medium-cost treatment Art/Cop may open new possibilities for the large-scale rearing of seahorses. Even the application of a low-cost Art diet might be appropriate for seahorse aquacultures as both survival and growth rates are only marginally lower compared to the former diet.

Effects of food type, temperature and salinity on the growth performance and antioxidant status of the longsnout seahorse,Hippocampus reidi

“…Food species influence on the growth rate and survival of newborn H. reidi were reported in several previous studies (Olivotto et al., 2008; Schubert, Vogt, Eder, Hauffe, & Wilke, 2018). Schubert et al (2018) reported that H. reidi larvae fed either diets of Selco S. presso‐enriched Artemia nauplii and a mixed diet of Artemia and copepod ( Eurytemora affinis ) had good survival, but the diet mixture resulted in superior weight and height growth. Different effects of food species and feeding stratagems on H. reidi growth and survival was also found by Olivotto et al.…”

Use of Artemia supplemented with exogenous digestive enzymes as sole live food increased survival and growth during the larviculture of the longsnout seahorse Hippocampus reidi

“…In recent years, studies have focused on the use of wild zooplankton or cultured copepods to improve survival and growth during the larviculture of H. reidi (Hora & Jouyex, ; Olivotto et al, ; Randazzo et al, ; Schubert, Vogt, Eder, Hauffe, & Wilke, ; Souza‐Santos et al, ; Willadino et al, ). Despite the benefits of these types of live food, they present a number of disadvantages such as risk of contamination with pathogens (Conceição, Yúfera, Makridis, Morais, & Dinis, ; Su, Cheng, Chen, & Su, ), variable composition (Hoff, Snell, & Neslen, ) and seasonality (Knuckey, Semmens, Mayer, & Rimmer, ), as in the case of wild zooplankton difficulties in mass production, high cost and intensive work for copepod cultivation (Knuckey et al, ; Vu, Jepsen, & Hansen, ).…”

Turnover Rates and Diet-Tissue Discrimination Factors of Nitrogen and Carbon Stable Isotopes in Seahorse <em>Hippocampus reidi</em> Juveniles Following a Laboratory Diet Shift

“…The results achieved on biological indicators such as growth and mortality as well as on the contribution of growth and metabolism to tissue turnover demonstrate that extending the feeding on copepods from 6 DAR to 11 DAR enhanced the overall condition and welfare of H. reidi juveniles. Due to the high cost of copepod production, a co-feeding regime including copepods-Artemia has been proposed for large-scale ex-situ production [65].…”