Balaenoptera omurai

Status and Conservation. CITES Appendix I. Classified as Data Deficient on The IUCN Red List. Omura’s Whale was only recently described as a species, and it is assigned a Data Deficient category because its global population size is unknown and its true biogeographical distribution has not yet been determined. The only available estimate of regional population size is from sightings data of “ small Bryde’s Whales ” reported in 1980 in waters around the Solomon Islands. This report estimated the regional population of these smaller rorquals at 1800 individuals. Because Omura’s Whale was only formally identified in 2003, there is no dependable information concerning the possible impacts of commercial whaling on its populations. It is clear, however, that individuals were killed under “ scientific permits ” in the 1970 s. There also are recent reports of accidental entanglement in Japanese set nets and captures by the Philippine artisanal whale fishery. As with other species of rorquals, the international moratorium on commercial whaling represents the primary conservation measure for insuring the survival of Omura’s Whale. Other threats include fatal encounters with vessels (ship strikes), anthropogenic impacts (commercial shipping noise), and kills for “ scientific research. ” Threats posed by climate change to the warm-water Omura’s Whale are probably not as great as for more pagophilic species of rorquals.

Sumber: Balaenopteridae

Descriptive notes. Total length 1000 - 1200 cm. No specific data are available for body weight. Existing data suggest that adult female Omura’s Whales are larger than adult males. The smallest known neonate was 320 cm in total length. Omura’s Whale has traditionally been confused with whales of the Bryde’s Whale (B. edeni) complex and the Sei Whale (B. borealis), and it was often referred to in older whaling literature as “ smallform Bryde’s Whale ” or “ pygmy Bryde’s Whale. ” Body coloration of Omura’s Whale is distinctly countershaded, with a blue-black to dark-gray back and whitish-beige to cream-colored ventral surface. Undersides of pectoral flippers and caudal flukes are also light-colored like belly. As in Fin Whales (B. physalus), external surface of the lowerjaws shows coloration asymmetry, being black to dark gray on the left side and whitish-beige to cream-colored on the right side. External body proportions are reported to be similar to members of the Bryde’s Whale complex. Unlike formsin the Bryde’s Whale complex, rostrum of Omura’s Whale has only a single, prominent median ridge extending from blowholes to tip of rostrum, and it lacks distinct right and left lateral rostral ridges. From above, lateral margin of rostrum of Omura’s Whale is distinctly convex and reminiscent of the U-shaped rostrum of Blue Whales (B. musculus). Dorsal fin is relatively small, low, and strongly falcate. Pectoral flippers are small and slender, relatively longer than in forms of the Bryde’s Whale complex. There are four digits in the manus, and phalangeal formula of the type specimen is: II- 5, 111 - 7, IV- 6, and V- 3. There is no available description of size and shape of caudal flukes. Ventral groove blubber is marked by 80 - 90 longitudinal grooves that extend posteriorly to and slightly beyond umbilicus. Coloration of baleen laminae is bilaterally asymmetrical. On the right side, anterior 30 % of rack is yellowish-white, posterior 20 % is black, and middle 50 % is bicolored. On the left side, anterior 85 % of rack is bicolored, while posterior 15 % is black. Baleen laminae are relatively wide at the base, with a reported length-to-width ratio of only 1 - 2: 1. Largest main baleen plates are 23 - 28 cm in length. Number of baleen laminae in the type specimen is 203 on the right side and 208 on the left. This count represents the fewest laminae per side of any known species of rorqual. Swimming speed of Omura’s Whale has not been reported, nor has the nature ofits blow. Dorsal fin is visible when an individual dives.

Sumber: Balaenopteridae

Distribution. Tropical and subtropical waters of the Indo-Pacific region extending to 34 ° Nand 12 ° S.

Sumber: Balaenopteridae