Expanding Spiny Lobster Aquaculture in Nigeria

Expanding Spiny Lobster Aquaculture in Nigeria

Chapter One of Expanding Spiny Lobster Aquaculture in Nigeria

INTRODUCTION

BACKGROUND TO THE STUDY 

Spiny lobsters are of two different species known as Panulirus homarus and Panulirus ornatus with cylindrical shaped body comprising cephalothorax, heavily spined and conspicuously marked by two frontal supra-orbital horns; abdomen smoother, having six somites with no distinct rostrum (Priyambodo & Jaya, 2010). They are characterized with large antennae with basal segments well developed and spined, flagellum stiff, robust and longer than body (Thuy & Ngoc, 2004). However, Nigerian fish farmers has been diversifying and investing hugely in spiny lobster aquaculture all over the country. Of the two species of spiny lobster, Panulirus homarus is emerging as the favoured specie for aquaculture in Nigeria. This is based on a number of factors including market demand and pricing, availability of naturally settling seed (for on-growing), development of hatchery technology, suitability for captive grow-out and adaptability to a variety of production systems (Hart, 2009). According to Peterson & Phuong (2011), aquaculture production of lobsters is an attractive proposition worldwide, as the species are generally of high value and in great demand, and fishery production cannot be increased. Active research and development programmes throughout the world have sought to develop this sector, but to date none have been successful, beyond the developments been practiced in Nigeria.
Jones (2010) also opined that tropical species of spiny lobsters are likely to remain at the forefront of aquaculture production development because of the availability of wild seed, the development of commercially viable hatcheries, and their highly economic grow-out characteristics. The expansion and development of spiny lobster culture has been actively pursued in Nigeria for many decades, although advances have been slow to realize because of the protracted larval phase. To date the only significant established lobster aquaculture industry in the country is that of tropical region, based on the grow-out of wild caught juveniles. Based on the fact that spiny lobsters are reef dwelling species, most abundant on coral and coastal fringing rocky reefs and the areas surrounding them. They are less commonly found in inshore areas of a sedimentary nature, indicating their broad environmental tolerances that make them suitable for aquaculture. They are found in depths of 1 to 50 m.
The juvenile and adult stages of both species are omnivorous, grazing primarily on small crustaceans, molluscs, worms and algae (Tuan & Mao, 2004). They are generally nocturnal, most active from dusk through to dawn. Both are highly social, preferring to congregate in groups in hollows, caves and crevices within and beneath the reef structures. This social nature also confers a distinct advantage for aquaculture which can likely encourage the expansion of the spiny lobsters farming in Nigeria. Another factor to consider in the expansion of Lobster farming is that it is currently reliant on a natural supply of wild pueruli (young, transparent lobster from the larvae), which in Nigeria comprises a fishery that employs a range of gear and methods to attract and capture the swimming pueruli as they move inshore after their oceanic larval stage. In Nigeria, two to three million pueruli are caught each year between October and March, of which around 70 per cent are Panulirus ornatus and 25 per cent Panulirus homarus.
The captured pueruli are very delicate and mortality can be very high (>50 percent). For the purpose of expanding spiny lobster aquaculture, pueruli are purchased from the fishers by Nigerian dealers, who hold and transport them to nursery farmers. The bulk of pueruli are transported in small styrofoam boxes by motorbike over distances of up to several hundred kilometres. The nursery phase typically involves stocking the pueruli at 50-100/m2 into submerged cages, consisting of mesh surrounding a steel frame. Each cage is placed on the sea floor at 2-5 m depth and a feeding tube from the surface to the cage provides the means to feed the baby lobsters. Finely chopped trash fish, crustaceans and molluscs are used as food. The nursery phase lasts for 3-6 months, during which the lobsters grow to 10-30g. They are then harvested and moved to grow-out cages. Mortality during the nursery phase may be as high as 40 per cent but under optimal conditions is usually less than 10 per cent (Williams, 2009).

STATEMENT OF THE PROBLEM 

Overgrowing technique, feed supply, handling and processing, production cost, disease control and measures and marketing strategies are the factors to consider in the quest of expanding spiny lobster aquaculture in Nigeria. However, the primary constraint to industry expansion is the availability of seed. Reliance on wild seed is risky, and while the Nigerian farmers have made great use of a natural seed resource to establish the industry, its long term future can only be secured with a hatchery supply. Fortunately, research efforts (even in advanced countries) in tropical spiny lobster hatchery technology are nearing a commercialisation phase, so it is likely that by 2017-2020, the expansion of spiny lobster farming will no longer be constrained by the seed supply.
Disease is also a major constraint and spiny lobster farming in Nigeria has already experienced the severity of a disease outbreak. The positive effect of this has been that spiny lobster diseases are better understood, and prevention and treatments have improved. Hopefully the Nigerian experience will be instructive to other countries in planning, managing and expanding the development of the industry.