Coastal Aquaculture and Mariculture

Unit 5- Major groups of Fisheries in India

5.3.5b. Perches
The group of fishes popularly called perches (Order: Percifonnes) include more than 20 families such as Serranidae (rockcods/groupers), Lutijanidae (snappers), Lethrinidae (pigface breams) (called major perches in view of their large body size), Nemipteridae (threadfin breams/pink perch), Haemulidae (grunts/ sweetlips), Caesionidae (fusiliers), Priacanthidae (bulls eye), Aunthridae (surgeonfishes) and Siganidae (rabbitfishes/spine-foot) (called minor perches in view of their smaller body size). The group that includes the families Sparidae, Drepaneidae, Ephippidae, Centropomidae, Lobotidae, and Scatophagidae represents all other perches.
Distribution
Perches occur all along the Indian coast. Most of the species belonging to this group inhabit the rocky grounds and the coral reef areas, while a few prefer the seagrass beds and muddy and sandy bottoms. They are particularly abundant in the rocky and coral grounds off Kerala, off Tamilnadu, (Gulf of Mannar) Gulf of Kutch, off Paradeep and in the Andaman Seas. The major species of perches are bottom dwellers and they usually inhabit rocky and coral areas. The 100 km long Wadge Bank extending from Kovalam (South west coast) to Kanyakumari is rocky and the crevices and outcrops in this area provide a congenial habitat for many species of major perches. The grouper grounds are located in the depth range of 75-100 m along the 1,000 km long southwest coast between 80 N (Kanyakumari) and 13°N (Mangalore). These grouper grounds are small areas of hard bottom with shallow ridge-like outcrops, which rise 2-5 m from the ground level and have very irregular profile. The thread fin breams occur on muddy and sandy bottoms in the coastal inshore as well as offshore shelf waters. Although they occur mostly in shallow waters between 5 m and 80 m depth, they are recorded up to about 300 m depth. In the shallow waters up to 40 m depth, the resource is dominated by N. japonicus whereas in the deeper zones (beyond 40 m depth) N. mesoprion is the dominant species.
Potential
As per recent estimate by the Government of India the catchable potential of all the perches within the 50 m depth zone is about 1,14,000 t and that beyond 50 m, it is 1.25,000 t, total being 2,39,000 t. Within the former zone, southwest is the most productive followed by southeast and northwest. The rocky grounds of Wadge Bank about 12,000 km2 and Quilon Bank about 3,300 km2 are found to be rich for the major perches. Although accurate estimates are not available, it appears that about 40,000 - 60,000 t can be caught per year additionally. Since these grounds are not trawlable, their exploitation is possible only by drift nets, hooks & lines and traps. Potential exploitable resources of pink perch (Nemipterids) have been located in slightly deeper waters beyond the reach of traditional gears.
Production trend
These larger perches constitute roughly 2% of the total marine fish production in the country, with an average annual landing of 28,800 t during 1990- 2000 period. Statewise, the highest share was from Tamil Nadu (about 50%) followed by Kerala (about 20%), Gujarat (about 11%), Maharashtra (about 8%), Karnataka (about 6%) and Andhra Pradesh (about 5%). Along the coasts of Orissa and West Bengal the fishery for these resources is very negligible. The average perch production during 1985 - 89 was 89,100 t and the same was 1.97,100 t during 2000 - 04. Perch fishery is dominated by the threadfin breams with landings of 1, 11, 345 tonnes annually and forms 57% of the total perch catch.
There is an organized fishery for major perches in Tamil Nadu, along the Gulf of Mannar and the Wadge Bank. Both mechanized, as well as non-motorised traditional units in operation employ gears such as hooks and lines, long lines, gill net and trawl. The annual catch of major perches along southeast and southwest coasts varied from 5,114 t to 17, 863 t during the years 1990-2000. The catch consisted of pig face breams (63%), rock cods (about 24%), and snappers (about 12%) in the order of abundance.
Recent production
The potential yield and yield of these groups in the last ten years are given in the following table.
Potential yield and catch of perches during 1997 -2006

Species composition of important perches
There are 449 species under 62 genera in the family Serranidae worldwide. Of the several species available in India, seventeen species of groupers constitute the fishery in India. They include Epinephelus tauvina (Greasy grouper). E, malabaricus (speckled grouper), E, bleekeri (Dusky tail grouper). E. areolatus (Areolate grouper), E. diacanthus (six banded reef cod), E. episticus (Broken line grouper), E. fasciatus (Red banded grouper), E. flavocaeruleus (Blue and yellow reef cod), E. morrhua (Banded cheek reef cod), E. undulosus (Brown lined reef cod), E. merra (Wire netting reef cod), E. fuscoguttatus (Brown marbled grouper), E, chlorostigma (Brown spotted grouper), E. longispinis (spotted grouper). E. lanceolatus (Giant grouper), Cephalopholis sonnerati (Red coral cod) and Cephalopholis boenack (Blue lined seabass).
There are 103 species under 17 genera of the family Lutjanidae worldwide. Of the several species of snappers available in India, fourteen species of snappers form the fishery. They include Lutjanus johni (John's snapper). L. argentimaculatus (Red snapper), L. gibbus (Hunched snapper). L. bohar (Two spot snapper), L. rivulatus (Blue-lined snapper), L. bengalensis (Bengal snapper). Lutjanus lutjanus (Bigeye snapper), L. fulviflammus (Black snapper), L. kasmira (Blue and yellow snapper), L. sebae (Emperor snapper), L. sanguineus (Red snapper), L. russeli (Russel's snapper), L. malabaricus (Malabar snapper) and Pristipomoides typus (Sharp tooth snapper).
There are 39 species belonging to five genera in the family Lethrinidae worldwide. Of the several species of emperors available in India, nine species constitute the fishery. The representatives of the Family Lethrinidae include Lethrinus nebulosus (Starry emperor bream), L. obsoletus (Yellow banded emperor bream), L. microdon (Long face pigface bream), L, miniatus (Long nosed emperor bream), L. nebulosus (Bridle pig-face-bream), L. mahsena (Skuy emperor), Lethrinus onrnatus (Ornate emperor), L. semicinctus (Black blotch emperor) and L. variegatus (Slender emperor).
There are 62 species under five genera in the family Nemipteridae worldwide. Of the several species of thread fin breams, six species constitute the nemipterid fishery in India. They are Neimpterus japonicus, N. mesoprion, N. delagoae, N. tolu, N. luteus and N. metopias. Of these six species of threadfin breams (Family Nemipteridae), Nemipterus japonicus (Japanese threadfin bream) and N. mesoprion (Red filament threadfin bream) are the commercially important species.
Size composition
Among perches, the family Serranidae (Rock cods or groupers) has the dominant sizes in the fishery ranging from 250-670 mm, the family Lethrinidae (pigface breams) fishery is supported by fishes in size ranging from 220- 750 mm, the family Lutjanidae (snappers) by fishes of 220- 700 mm and the family Nemipteridae (Threadfin breams) by fishes of 180 -250 mm.
Fishing season
Peak production of perches along the Tamil Nadu coast is from December to April although good landings are recorded throughout the year.
Mode of exploitation
Most of the fishing grounds being not amenable to trawling operations, the major perches are exploited mainly by other gears like gill nets, hooks and lines, traps and drift nets.
Age and growth
The maximum size of fishes within this group ranges from 18 cm (Nemipterus mesoprion) to 221 cm (Epinephelus lanceolatus).
Food and feeding
Perches are predatory fishes, mainly feeding on other fishes such as Therapon spp., Ambassis spp., etc. and invertebrates such as crabs, prawns, stomatopods etc. Cephalopods are also found in the diet of some perches.
Spawning season
The spawning season varies from locality to locality and among different species. For instance, N. japonicus spawn during June -September along the northwest coast and during November -April along the southeast coast. N. mesoprion spawn during November -March.
Utilization and marketing
The major perches are high-value fishes and are exported to different countries. It is possible to export them in live condition, as live fishes command very high price in the foreign markets. A live grouper fry (usable for aquaculture) commands a price of 1 US $, a fingerling 3 $ and a 600 g adult 20 $/kg. India exported a few consigmnents of groupers in live or fresh-chilled condition through cargo vessels in 1996-97, but discontinued the export due to various constraints.
Conservation and management
Information available on the biology and stock assessment of perches is scanty. Based on the species for which reproductive biology has been studied, it is evident that the groupers are protogynous hermaphrodites. After spawning for one or more years, the female groupers change sex and function as males. At sexual transition, the oocytes degenerate, the spent1atogonia proliferate and the ovary is transformed into a functional testis. Evidences of the ovarian origin of the testis are the remnants of oocytes and the ovarian lumen. The groupers spawn several times in a year. This protogynous mode of reproduction poses several problems in the aquaculture of groupers as well as in the fishery management practices. Estimates on the stocks of the major perches along the Indian coast are not available. Considering the vulnerability of the adult population, especially of the male population, and the export-oriented target fishing, the biological characteristics and the stocks of the major perches need to be assessed for the Indian coast.
Information available on the biology and stock assessment of emperors, snappers and threadfin breams are very much limited. Information available for some species is in the form of fragments. They need to be consolidated. Hence, research work need to be undertaken on the food and feeding habits, stock assessment, Maximum Sustainable yield of these species in order to make strategies and formulate policies for the improvement of production of perches. In addition, possibilities need to be explored for the mariculture of these perches in commercial scale.
There is a wide gap between estimates of potential yield and present yield of perches from the Indian waters. There is a vast scope for increasing the catch of this multispecies resource. Possibilities need to be explored to improve the catch of perches by supplementing catch from Northwest and Northeast regions through location of new potential perch grounds in these regions. Suitable fishing methods need to be designed and advocated to exploit perches from the non- trawlable fishing grounds. Meanwhile, it is important to understand that few species like Epinephelus diacanthus and Lethrinus nebulosus are under high fishing pressure. The ways and means need to be found out for the protection of these species.
It should be realized that fisheries need to be viewed from an ecosystem perspective. Demersal fish species do not live by themselves. Rather, they are embedded in ecosystems where they perform their roles as consumers and prey of other organisms. For describing the ecosystem impacts of fisheries, it is necessary to concentrate on the impacts of fisheries on food webs, i.e. on the network of flows of matter, which in ecosystems, links the plants with herbivores, and the latter with their predators. These networks of flows are affected directly by fishing, which removes predatory fish, or competes with them to their preys, in either case affecting the web within which predators and preys are embedded.