World Status, Exploitation and Trade - WIDECAST

MEXICO( Chelonia mydas or perhaps Eretmochelys ) in a night on the Tres MariasIslands. This harvest must have been intermittent and seems highly unlikelyto have had a detrimental effect on turtle populations.Large-scale commercial exploitation of Green Turtles in the northern Mexicanfeeding grounds evidently began in the 19th century, considerably earlierthan at the Michoacan nesting grounds. It is implied (though not definitelystated) in both Parsons (1962) and Cliffton et al (1981) that until the1950s most commercial harvesting was on the west (Pacific) coast of BajaCalifornia.Parsons (1962) notes that a turtle cannery, run by a Joseph P. Hale of SanFrancisco, wfi? in ope-ation in 1891 on a small island in Bahia Magdalena,some 250 miles (400 km) south of Turtle Bay on the west coast of BajaCalifornia; at this time canned "extract" of Green Turtles was exported toEngland and live turtles were shipped to San Francisco. By 1906 the cannerywas reportedly abandoned, although monthly shipments of live Green Turtleswere still being made to San Francisco on ships of the Pacific CoastSteamship Company (Parsons, 1962); concern was already being expressed thatunrestricted exploitation would result in the destruction of the resource(Parsons, 1962). Shortly afterwards San Diego developed as a fishing andcanning centre; O'Donnell (cited in Cliffton et al , 1981) estimates thatc. 1000 live turtles per month were sent to San Diego from Scammon's Lagoon(Laguna Ojo de Liebre) in the early years of the century. In 1920 some15 000 cases of turtle were reported canned in San Diego plants (presumablymost or all from Mexico, and most likely to have been C. mydas ); howeverMexican legislation brought an end to this industry by 1923 (Parsons, 1962).B. 1948-presentFigures for the Mexican turtle fishery from 1948-73 are summarised inMirquez (1976a). Figures for Chelonia are given under C. mydas andC. agassizi ; it is assumed that those for C. mydas apply to the Caribbeanand Gulf of Mexico Green Turtle populations and those for C. agassizi tothose of the Pacific and Gulf of California.MArquez, writing in 1976, characterised the Mexican Turtle fishery for 1948to 1974 as falling into four main phases:i. Relatively low, stable (i.e. sustainable) harvest for 1948-59;ii. Harvest tending to increase, from 1960 to 1966;iii. Maximum exploitation 1968-69;iv. Rapid decline in harvest from 1969 to 1974, with a slight tendencytowards stabilisation;This trend is followed relatively closely by the Pacific C. mydas fisheryalthough the fishery has fluctuated in importance (in terms of recordedvolume of production) compared with harvests of other species andpopulations. Thus for the period 1948-1955 harvest of Caribbean and Gulf ofMexico C. mydas appears to have been of greater importance (total recordedfresh meat production of 530 tonnes for Pacific C. mydas compared with 2020tonnes from the eastern seabord of Mexico for 1948-55). From 1956 to 1963Pacific C. mydas was the most important component of the Maxican Turtlefishery. Official live weight production of 3430 tonnes compared with 2245tonnes from C. mydas from the eastern seabord and 1830 tonnes of361