Fisheries in atolls- Tradeoffs between harvest and conservation

Atolls are ring shaped coral reefs including a coral rim that encircles a lagoon partially or completely and with or without a coral island/cays on the rim. Most of the world’s atolls are in the Pacific Ocean and Indian Ocean. Lakshadweep islands, Maldives and the Chagos Archipelago are the atolls in the Indian Ocean. Lakshadweep are the only atoll islands in India. They lie scattered in the Arabian Sea between Latitude 8.26° to 12.4° N and Longitude 71.7°-73.75° E, comprising of 36 islands, 3 reefs and 5 submerged banks. These islands consist of coral formations built upon the Laccadive-Chagos submarine ridge rising steeply from a depth of about 1500 m to 4000 m off the west coast of India. While the total land area is 30 sq.km, the length of the coastline is 132 km and lagoon area of 4200 sq.km. Its territorial water spread is 20000 sq.km and it constitutes 0.4 million sq.km to the EEZ of Indian Union. Out of the 36 islands, 11 are inhabited with a population of 64,473 (2011 census). The atolls have 4 distinct biomes comprising of the islands, lagoons, reefs and the Open Ocean. Few threats to the atoll systems are sea level rise, salt water intrusion, reduced availability of fresh water, coral bleaching, disturbances to reef ecosystem, shrinking of livelihood and excessive dependence on external resources, excessive harvest of reef resources etc

Morphological differentiation of closely resembling ariid species, Arius venosus and A. sumatranus

In Indian waters ariids (Siluriformes/ Ariidae) are represented by 9 genera and 25 valid species. The genus Arius is the most diverse with eight species reported from Indian waters which can be categorised in two broad groups. One having elongated teeth patches with globular teeth comprising of five species- A. jella, A. maculatus, A. gagora, A. malabaricus and A. arius is clubbed under maculatus complex. Other group included species like A. subrostratus, A. sumatranus and A. venosus having smaller teeth patches with villiform teeth (non-maculatus complex) (Dhanze and Jayaram. 1982). The non-maculatus complex does not contribute much to the commercial fishery barring A. subrostratus which forms minor fishery along southwest coast of India. A. subrostratus can be easily differentiated from rest of the con-generic members by smaller barbels and long snout with small mouth

Oil Spill Occurrences along Indian Exclusive Economic Zone

Oil Spill Occurrences along Indian Exclusive Economic Zon

Red-toothed triggerfish emerges as the popular live bait for handline based yellowfin tuna fishery in Lakshadweep

Live-bait is an integral part of pole and line tuna fisheries of Lakshadweep waters. Nearly 14 species belonging to families Dussumieriidae, Apogonidae, Caesiodidae, Pomacentridae, Emmelichthyidae and Atherinidae are collection island to island and seasonal variations in species dominance. Spratelloides spp., Apogon spp., Archamia spp, Ceasio spp., Pteroceasio spp., C caeruleus, L. tapainosoma and Spratelloides delicatulus are the most dominant live-bait species across atolls

Emergence of night fishing using LED lights for live-baits in Lakshadweep

The pole and line fishery for skipjack tunas depends totally on consistent supply of live–bait fishes. Small sized fishes belonging to the families clupeidae, apogonidae, pomacentridae, ceasionidae, atherinidae etc constitutes the bait fishes

Reproductive biology, diet and feeding pattern of longtail tuna Thunnus tonggol (Bleeker, 1851) in the north-eastern Arabian Sea off Gujarat, India

Longtail tuna Thunnus tonggol (Bleeker, 1851) is the major tuna resource in the neritic realms of the northern Arabian Sea and forms considerable fishery in the coastal nations in the region. Gujarat, on the north-west coast is the major province landing longtail tuna in India. The paper attempts to add to the hitherto sparse knowledge base on biology of the longtail tuna fished along the north-west coast of India, through a study spanning from 2011 to 2015. Reproductive biology, spawning, food and feeding dynamisms of the species were investigated. Sex ratio of the species was estimated as 1:2.1 and depicted an increase in male preponderance as the size increased. The fish attains maturity at 607 mm and it spawns during summer months starting from May. The fish is typically a non-selective feeder and over 22 taxa comprising of fishes, cephalopods and crustaceans formed the diet at varying rates over the year. Variation in feeding intensity at different reproductive stages is discussed besides the constraint posed by the large presence of unidentifiable, partially digested gut content

Taxonomic note on the Indian species of genus Netuma

In Indian waters, genus Netuma is represented by two species namely N. bilineata and N. thalassina (Order: Siluriformes, Family: Ariidae). Rounded shout, thin lips, inconspicuous median longitudinal groove, and higher anal fin ray count (16-19) are characters of N. bilineata while N. thalassina has conical snout, clearly visible median longitudinal groove and lower anal fin ray count (13-15). Prior to the erection of N. bilineata (earlier considered as synonym of N. thalassina) as valid species, Indian workers had difference of opinion regarding the representation of species under this genus from Indian waters

Non-target species interactions in tuna fisheries and its implications in fisheries management: Case of large-mesh gillnet fisheries along the north-west coast of India

Occurrence of non-target, associated and dependent species is a feature of tuna gillnet fisheries world-over, posing a great concern for fisheries management. Predominance of small-scale or artisanal fisheries in the region compounds the concern due to the uncertainty in data. There is dearth of information on the catches and the non-target species interaction in the tuna gillnets fisheries in India, especially from the north-west coast, where gillnet is the predominant gear targeting the tuna. We collected spatially explicit catch data with voluntary participation of fishermen from Veraval, Gujarat and quantified the species wise catches over space and time for 567 fishing operations spread across six years (2011-2016). Species composition, seasonal variation, nature and level of interrelationship in catch incidences, similarities among different groups of resources etc. were ascertained using various statistical tests like the Kruskal-Wallis rank test, Pearson’s correlation and principal component analysis (PCA). The study reveals spatial expanse of gillnet fisheries of Gujarat and their major fishing grounds together with variations in catches of different groups over space and time. Nature and strength of interaction of sensitive species like turtles and dolphins as well as the unicorn leatherjacket, an emerging catch in the gillnet tuna fisheries was ascertained and GIS maps depicting the areas of copious presence of these groups are presented. Management implications of such interactions as well as the potential of involving fishermen to gather spatially explicit fishery data, paving way for their active Available online at: www.mbai.org.in doi: 10.6024/jmbai.2018.60.1.2047-03 involvement in fisheries governance are discussed. The study can be replicated at national level to enhance the understanding on the gillnet fisheries to bring in pragmatic interventions to sustain the fisheries

A genetic network mediating the control of bud break in hybrid aspen

In boreal and temperate ecosystems, temperature signal regulates the reactivation of growth (bud break) in perennials in the spring. Molecular basis of temperature-mediated control of bud break is poorly understood. Here we identify a genetic network mediating the control of bud break in hybrid aspen. The key components of this network are transcription factor SHORT VEGETATIVE PHASE-LIKE (SVL), closely related to Arabidopsis floral repressor SHORT VEGETATIVE PHASE, and its downstream target TCP18, a tree homolog of a branching regulator in Arabidopsis. SVL and TCP18 are downregulated by low temperature. Genetic evidence demonstrates their role as negative regulators of bud break. SVL mediates bud break by antagonistically acting on gibberellic acid (GA) and abscisic acid (ABA) pathways, which function as positive and negative regulators of bud break, respectively. Thus, our results reveal the mechanistic basis for temperature-cued seasonal control of a key phenological event in perennial plants