I - K

Marine Wildlife on Tobago's Shores - Listed in alphabetical order started with "I - K"

• Istiophorus albicans

  Istiophoridae (Billfishes)
  
  Common name: Atlantic sailfish

  Class: Actinopterygii (ray-finned fishes)

  ORDER: Perciformes

  Maximum size: 315cm long (male/unsexed); maximum weight: 59kg

  Environment: pelagic; marine; depth range -40m

  Climate: subtropical; 21-28°C; 50°N-40°S

  Importance: fisheries: commercial; gamefish: yes

  Distribution: Atlantic: in tropical and temperate waters approximately 40°N in the western North Atlantic, 50°N in the eastern North Atlantic, 40°S in the western South Atlantic, and 32°S in the eastern South Atlantic. Migrating to Mediterranean Sea, mostly based on juvenile specimens. Highly migratory species, Annex I of the 1982 Convention on the Law of the Sea. Some authors recognise a single worldwide species, I. platypterus (Shaw 1792) but Nakamura 1990 is used retaining the usage of I. platypterus for the Indo-Pacific sailfish and I. albicans for the Atlantic sailfish in recognition of differences between them.

  Diagnosis: Dorsal spines (total): 0-0; Dorsal softrays (total): 48-53; Anal spines: 0-0; Anal soft-rays: 9-12; Vertebrae: 24-24. Biology: Usually found in the upper layers of warm water above the thermocline, but also capable of descending to rather deep water. Often migrates into near-shore waters like those of Tobago. Occasionally forms schools or smaller groups of 3-30 individuals, but often occurs in loose aggregations over a wide area. Feeds mainly on small pelagic fishes but also takes bottom-dwelling organisms. Utilised fresh, canned and frozen; eaten steamed.

  Threatened: Not in IUCN Red List

  Dangerous: harmless

• Katsuwonus pelamis

  Scombridae
  
  Family: Scombridae (Mackerels, tunas, bonitos)

  Common name: Skipjack tuna

  Class: Actinopterygii (ray-finned fishes)

  ORDER: Perciformes

  Maximum size: 108cm fork length (male/unsexed); maximum weight: 35kg; max. reported age: 12 years

  Environment: pelagic; marine; depth range 0-260m

  Climate: tropical; 15-30°C; 58°N-47°S

  Importance: fisheries: highly commercial; gamefish: yes

  Distribution: Cosmopolitan in tropical and warm-temperate waters. Not found in the eastern Mediterranean Sea and the Black Sea. Highly migratory species.

  Diagnosis: Dorsal spines (total): 14-16; Dorsal softrays (total): 14-15; Anal spines: 0-0; Anal soft-rays: 14-15; Vertebrae: 41-41. Interpelvic process small and bifid. Body scaleless except for the corselet and the lateral line. Swimbladder absent. The back is dark purplish blue, lower sides and belly silvery, with 4 to six very conspicuous longitudinal dark bands which in live specimens may appear as continuous lines of dark blotches.

  Biology: Found in offshore waters; larvae restricted to waters with surface temperatures of 15-30°C. Exhibit a strong tendency to school in surface waters with birds, drifting objects, sharks, whales and may show a characteristic behaviour like jumping, feeding, foaming, etc. Feed on fishes, crustaceans, cephalopods and molluscs; cannibalism is common. Preyed upon by large pelagic fishes. Also taken by trolling on light tackle using plugs, spoons, feathers, or strip bait. Marketed fresh, frozen or canned; also dried-salted and smoked. Spawns throughout the year in the tropics, eggs released in several portions.

  Threatened: Not in IUCN Red List

  Dangerous: reports of ciguatera poisoning