GROWTH AND SURVIVAL OF SPINY LOBSTER, Panulirus homarus JUVENILES FED WITH DIFFERENT FORMULATED FEEDS

Article Highlights
- Indonesia has remarkable natural resources of spiny lobster Panulirus homarus and an exceptional opportunity to establish the largest lobster aquaculture industry in the world.
- However, culturing lobsters still relies on natural feeds (trash fish of fresh fishery by-catch) which are inefficient and environmentally unsustainable.
- Developing formulated feed based on locally available ingredients is invaluable for replacing natural feeds to support sustainable lobster culture.
- Formulated feed made of local fish meal provided the best growth of juvenile spiny lobster Panulirus homarus compared to imported fish meal.

Abstract
Several studies suggested that good growth performance and survival of lobster juveniles can be achieved by feeding the lobsters with formulated feeds. This study aimed to (1) evaluate the growth and survival of spiny lobster Panulirus homarus juveniles fed with different diets having profiles based on a basal diet formulation and (2) to compare the growth of lobsters fed with an identical formulated feed with variations only in sources of fish meal and dry matter content. The feeding experiment was designed following a completely randomized design (CRD) with five diet treatments and five replicates for each treatment. Five experimental diets were prepared in this experiment, i.e., Diet A (basal diet prepared as moist pellets); Diet B (moist pellets with the same formulation as Diet A, using local fish meal); Diet C (moist pellets with the same formulation as Diet A, using imported fish meal); Diet D (dry pellets with the same formulation as Diet A, using imported fish meal); and Diet E (fresh fish). Juveniles of spiny lobster with an average weight of 3.00±0.07 g were allocated in 25 net cages (60 x 60 x 60 cm) placed in a circular HDPE canvas tank (7.5 m in diameter) at a density of 15 lobsters/cage in a flow-through seawater system. The juveniles were fed with the experimental diets twice/day for 12 weeks. The experiment showed that the best growth was observed in juveniles fed with moist feed containing local fish meal (Diet B) with the final weight reaching 18.74±2.30 g. Moist feed containing imported fish meal (Diet C) resulted in a higher survival rate (46.66%), and the lowest survival rate (13.33%) was obtained from juveniles fed with fresh fish (Diet E).

INTRODUCTION

Marine lobsters are highly favorable and considered prized luxury export products(, 2018), mainly exported to China, the United States of America, and Hong Kong. Chinese imports of lobsters increased dramatically to 38.6% or reached 11.461 MT from January to March 2021 compared to the same period in 2020(F.A.O., 2021). Grow-out culture of wild-captured spiny lobster juveniles to market size has been considered an evolving aquaculture industry in Asia, most markedly in Vietnam, and emerging in Indonesia(Nankervis & Jones, 2022). Indonesia has a remarkable natural resource of pueruli, and therefore, Indonesia has an exceptional opportunity to build the largest lobster aquaculture industry in the world(Priyambodo et al., 2020). In Indonesia, spiny lobster seed resources are found mainly in Lombok, Java, and Sumbawa Islands. In 2013-2014, the catch of lobster seeds was estimated to be over 3 million per year in Lombok(Bahrawi et al., 2015), and by 2016, more than 100 million lobster seeds were captured from Java, Lombok, and Sumbawa(Jones et al., 2019). Despite the growing lobster aquaculture industry, feeding in grow-out culture commonly relies only on fisheries products, such as trash fish or fresh fishery by-catch(Nankervis & Jones, 2022).

Fresh fishery products and trash fish for feeding in aquaculture have been well-identified as environmentally unsustainable and inefficient. For example, feeding with mussel flesh has a poor feed conversion ratio of up to 17.26:1(Rivaie et al., 2023). Trash fish as feed lead to significant water quality deterioration, causing environmental degradation and disease introduction(Nankervis & Jones, 2022). In addition, trash fish vary in their supply and nutritional profile. Moreover, there are difficulties in storage and possible spoilage during storage(Jones et al., 2015). The shrinking supply of trash fish and their downstream environmental effects have strengthened the urgency to develop sustainable formulated feeds(Nankervis & Jones, 2022). The development of formulated feed would provide benefits, such as nutrition optimization, feeding methods flexibility, easiness in usage and storage, waste minimization, and environmental sustainability improvement(Perera & Simon, 2014)for the development of lobster aquaculture(Saleela et al., 2015).

Some studies on formulated feed development and nutritional requirements for lobsters were conducted, such as studies on the appropriate level of protein for better growth and survival of spiny lobster P. homarus(Rathinam et al., 2014), and on the effects of binders on palatability and stability of formulated dry feed for P. homarus(Saleela et al., 2015). A review on the nutritional requirement and feed development for spiny lobster in post-larval stage reported that tropical lobster P. ornatus had the best growth when they were fed with a diet having a high digestible protein (> 56% DM) and 10-11% total lipid in dry matter(Nankervis & Jones, 2022). The use of moist pellets was also examined for the growth of lobster P. homarus(Ridwanudin et al., 2018). One of the major problems in aquaculture of spiny lobsters is an appropriate formulation of lobster feeds that are readily consumed, attractive, and stimulate optimal growth and survival(Marchese et al., 2019).

In a previous study, a basal diet formulation for 2-g lobsters had been developed and promoted good growth performance and survival rates of juveniles(Irvin & Shanks, 2015). This formulated feed was produced using ingredients sourced from Australia. Finding local, high-quality ingredients is the first step that needs to be addressed before Indonesian lobster farmers apply formulated feed for growing lobsters. Therefore, this study assessed 3-g lobster juveniles fed with a basal diet made from ingredients sourced from Australia and locally from Indonesia. This experiment was carried out to evaluate the growth and survival of 3-g lobster juveniles fed with different formulated feeds having a profile based on the basal diet, as well as to compare the growth of the lobsters fed with an identical formulated feed with variations only in fish meal sources and dry matter content.

MATERIALS AND METHODS

Study Location

The study was undertaken at the Institute for Mariculture Research and Fisheries Extension (IMRAFE), Gondol, Bali, Indonesia.

Rearing of Panulirus homarus Post-larvae to 3-g Juveniles

Feeding experiment was conducted by using P. homarus 3-g juveniles. To obtain the 3-g juveniles, pigmented P. homarus post-larvae were obtained from Lombok, West Nusa Tenggara Province, from which healthy post-larvae were selected to be reared up to juveniles weighing 3 g. The initial weight of the healthy lobster post-larvae was 0.2 g on average. Post-larvae rearing was conducted in floating net cages, concrete tanks, and an HDPE canvas tank with a flow-through seawater system. For the first 2 weeks, the post-larvae were fed with mysids and dry pellets and continued with dry pellets only until reaching 3-g juveniles. Grading of the post-larvae was carried out every 2 weeks to prevent cannibalism. Post-larvae rearing was conducted until the juveniles reached 3 g in weight. The 3-g juveniles were then used for the feeding experiment.

Figure 1.Feeding experiment using 3-g spiny lobster Panulirus homarus juveniles in 25 net cages

Feeding Experiment

The feeding experiment was designed following a completely randomized design (CRD) with five diet treatments and five replicates for each treatment. The experiment was carried out in 25 net cages (60 x 60 x 60 cm) that were placed in an HDPE canvas tank (Ø 7.5 m) with a flow-through seawater system, and equipped with aeration as oxygen supply

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