Anchovy Species Research Articles

Pseudonitzschia species found in digestive tracts of northern anchovies [Engraulis mordax)

The diatom species Pseudonitzschia australis Frenguelli has been implicated as the source of the domoic acid that contaminated anchovy species in Monterey Bay, California, during 1991. In other geographic areas, as well as in laboratory cultures of isolates obtained from various geographic areas, other Pseudonitzschia species have been shown to produce domoic acid. The stomach contents of anchovies caught in Monterey Bay during the following summer were analyzed to identify and determine the abundance of each of the Pseudonitzschia species present. Pseudonitzschia species present in net-tow samples taken at the same time from Monterey Bay were also recorded. In the stomach samples, nine different Pseudonitzschia species were found, including four that have produced domoic acid either under natural or laboratory conditions. These findings illustrate the risk of possible neurotoxin accumulation inherent in the diets of the anchovies studied. The planktophagous diet of the anchovies reflected the plankton composition of the surrounding water and also demonstrates the anchovies' ability to filter pennate diatoms from the near-surface seawater.

Validation of Daily Growth increments in Otoliths form Thrysa aestuaria (Ogilby), a tropical Anchovy from Northern Australia

Age and growth parameters were determined for the tropical anchovy Thryssa aestuaria from northern Queensland, Australia. Larval and juvenile forms of T. aestuaria, believed to be a single cohort recruited in the spring of 1990, were sampled between October 1990 and January 1991. Counts of growth rings in sagittal otoliths were determined for specimens from three of these samples. Comparisons of the different ring counts of fish from successive samples with the number of days elapsed between samples suggested that the growth rings examined were deposited daily. Two specimens of T. aestuaria marked with tetracycline hydrochloride in aquaria were found to deposit growth rings in the sagitta at a rate of one ring per day. Problems associated with reading daily growth rings in tropical anchovies are discussed in light of the results of this study. Growth in T. aestuaria is discussed in relation to reported growth information for other species of tropical anchovies.

Philippine small pelagic fisheries and their management

. A sampling survey of Philippine small pelagic fisheries was undertaken between 1987 and 1988 at eight sites in the Philippines. A description is given of the different fishing methods and estimates are made of catch per unit of effort and catch composition. Catches of sardines and anchovies dominated the landings of small-scale small pelagic gears whilst roundscads were an important catch component of large-scale fishing vessels. A first attempt to describe the overall species composition of the Philippine small pelagic landings was made using the sampling data and annual fisheries statistics for the years 1982-1986. Ten species of scad, mackerel and anchovy comprised 75% of the Philippine small pelagic landings. These results are discussed with respect to improving monitoring and sampling programmes designed to provide management-related information.

The voluminal changes of swim bladder of larval red sea bream Pagrus major.

Rearing experiments were made to determine the mechanism of diel swim bladder inflation and deflation in the red sea bream Pagrus major larvae. Swim bladder volume index (V/L3•10-6) was found to increase remarkably with growth during the larval stage, and remain nearly constant in the juvenile stage.The volume index was higher at night than in the day time under natural light conditions. However, under constant 24-h illumination such differences could not be observed. By changing the light conditions from dazk to light, the volume index decreased to half within 2h. Furthermore, with the reverse changing from light to dark, it increased to maximum level about lh after the onset of dark. Sealing the water surface of the tank with a layer of liquid paraffin, did not interfere with swim bladder inflation under dark condition and larvae clearly displayed the diel rhythm of night-inflation and day-deflation under natural light conditions.These results suggest that increase in the swim bladder volume in the physoclist species of red sea bream, is not caused by swallowing air at the water surface such as takes place in the physostome species of anchovy, but by the internal gaseous exchange mechanism of the swim bladder according to environmental light conditions.

Allozyme variation between populations of baitfish species Stolephorus heterolobus and St. devisi (Pisces : Engraulidae) and Spratelloides gracilis (Pisces : Dussumieriidae) from Papua New Guinea waters

Allozyme variation of two species of anchovies, St. heterolobus and St. devisi, and one presumptive species of sprat, Sp. Gracilis, was examined. Three populations of the two anchovies showed marked differences in the allele frequencies of two polymorphic enzyme loci: adenosine deaminase (Ada) and malate dehydrogenase (oxaloacetate-decarboxylating) (NADP+) (Mod) in St. heterolobus and adenosine deaminase and guanine deaminase (Gda) in St. devisi. It is proposed that populations of these anchovies are semi-isolated. The two colour morphs of Sp. Gracilis were observed in both populations studied. They appear to be fixed for alternate alleles in at least five enzyme loci and so are probably two separate species.

Anchoviella belizensis, a New Species of Anchovy from Belize, Central America, with Records of Associated Freshwater Species

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