The IUCN/SSC Shark Specialist Group
Shark News 12: November 1998
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The Shark and Skate Fishery in the Algerian Basin:
Biological and Technological Aspects
Farid Hemida, Laboratoire Halieutique, ISN-USTHB, Algeria
The demersal and pelagic fisheries operating off the coasts of Algeria
are multispecific (they take several species of fish at a time). Target
species and fishing grounds have remained the same since the early
1960s. However, the fishing gears used have changed over the years.
The traditional type of bottom trawl net, with a vertical opening of
about 2 m in height, is still in use. This mainly targets blue and red
shrimp Aristeus antennatus and deep-water pink shrimp Parapenaeus
longirostris in deep waters, and striped red mullet Mullus surmuletus,
red mullet Mullus barbatus and sparids in coastal waters . More
recently, new trawlers have begun using a second kind of trawl net,
the french net, which has a vertical opening of up to 10 m in height.
Boats equipped with french nets have more powerful engines than
boats which use the traditional trawl nets. French net catches include
demersal and some pelagic species, like european pilchard Sardina
pilchardus, european anchovy Engraulis encrasicolus and atlantic
horse mackerel Trachurus trachurus.
Trawl fishing is permitted in the coastal waters of Algeria from
August 31 to May 31. An intensive seine fishery also occurs throughout
the year. This last fishing activity takes place very close to the shore,
never more than 1 mile out to sea. The ring net boats spend no more
than 12 hours at sea during fishing trips; the trawlers are out of port for
20 to 24 hours.
A survey was carried out in September 1982 to evaluate the size
of stocks of small pelagic species. The estimation was up to 180,000
tonnes with a maximum sustainable yield of 30,000 tonnes. Small-scale
fisheries catch littoral and demersal species and some big
pelagic fishes such as tunas, swordfish and sharks (including blue
shark Prionace glauca, bignose shark Carcharinus altimus and
thresher Alopias vulpinus). Skates and demersal sharks are frequently
taken by the trawls and form a large part of the biomass, especially the
huge bluntnose sixgill shark Hexanchus griseus.
The Elasmobranch Survey
This project represents the first attempt to evaluate the dynamics of the
abundance and mortality of the sharks and rays which represent an
important part of fishing product in Algeria. These species are regularly
present in the markets and are consumed like the other commercial
fishes. However, until now no information about the biology and life
cycle of these species has been available in this country, so it has been
impossible to understand and predict the responses of their stocks to
exploitation. Fish stock assessment data (e.g. total length, total weight
etc.) have therefore been collected since October 1996. The length
frequency distributions collected have yet to be separated into male
and female records. However, length frequency distributions for three
species have been broken down into normal components using the
Bhattacharya's method (1967). The Von Bertalanffy growth parameters
were then estimated for smallspotted catshark Scyliorhinus canicula,
longnose spurdog Squalus blainvillei and gulper shark Centrophorus
granulosus.
We started a systematic survey of elasmobranchs occurring along
the Algerian coasts in 1996, recording the list of sharks and rays
present during regular visits to fish markets. Sixteen species of sharks
(from eight families) and eight species of rays (all genus Raja) have
been recorded, using international identification keys (Bauchot
and Pras 1980, Compagno 1984, Whitehead et al. 1986, Fisher et
al. 1987). Those elasmobranchs appearing in commercial catches from the Algerian basin are listed in Table 1. Photos are available for
most species, especially for Carcharinus altimus.
Table 1: List of the sharks and skates caught in the Algerian basin,
by all types of gear (up to October 1997).
| Order | Family | Species | Common Name |
| Hexanchiformes | Hexanchidae | Hexanchus griseus | bluntnose sixgill shark |
| | Lamnidae | Isurus oxyrhincus | shortfin mako |
| | Alopiidae | Alopias vulpinus | thresher shark |
| | Sphyrnidae | Sphyrna zygaena | smooth hammerhead |
| Galeiformes | Carcharinidae | Carcharinus altimus | bignose shark |
| | | Prionace glauca | blue shark |
| | Scyliorhinidae | Scyliorhinus canicula | smallspotted catshark |
| | | | Scyliorhinus stellaris | nursehound |
| | | | Galeus melastomus | blackmouth catshark |
| | Triakidae | Galeorhinus galeus | tope shark |
| | | | Mustelus mustelus | smoothhound |
| | | | Mustelus mediterraneus | blackspotted smoothhound |
| Squaliformes | Squalidae | Squalus blainvillei | longnose spurdog |
| | | | Squalus acanthias | piked dogfish |
| | | | Centrophorus granulosus | gulper shark |
| | | | Dalatias licha | kitefin shark |
| Rajiformes | Rajidae | Raja asterias | starry ray |
| | | | Raja miraletus | brown ray |
| | | | Raja clavata | thornback ray |
| | | | Raja oxyrhincus | longnosed ray |
| | | | Raja alba | white skate |
| | | | Raja montagui | spotted ray |
| | | | Raja radula | rough ray |
| | | | Raja undulata | undulate ray |
The great morphological similarity between some species of rays
makes their identification particularly difficult and uncertain.
Systematic keys based only on external morphological characteristics
do not help. We are therefore analysing biometric parameters and will
also attempt a biochemical systematic investigation to give, if possible,
improved precision at taxonomic level.
Finally, data obtained from a trawl-survey (ISTPM 1982) have
been used to determine the geographical and depth distribution of
eight species of shark (smallspotted catshark Scyliorhinus canicula,
blackmouth catshark Galeus melastomus, tope shark Galeorhinus
galeus, smoothhound Mustelus mustelus, blackspotted smoothhound
Mustelus mediterraneus, longnose spurdog Squalus blainvillei, gulper
shark Centrophorus granulosus, velvet belly Etmopterus spinax) and
five species of rays (starry ray Raja asterias, brown ray R. miraletus,
thornback ray R. clavata, longnosed ray R. oxyrhincus, and spotted
ray R. montagui) .
References
Bauchot, M.L. and Pras, A. 1980. Guide des poissons marins d'Europe .
Delachaux & Niestlé (ed), Neuchatel: 427 pp., 67 pl.
Bhattacharya, C.G. 1967. A simple method of resolution of a distribution into
Gaussian components. Biometrics, 23: 115-135.
Compagno, L.J.V. 1984. Sharks of the world. An annotated and illustrated
catalogue of shark species known to date. FAO Fisheries Synopsis 125,
Vol.4, Part 1 & 2: pp 1-249 and 251-655.
Fisher, W., Bauchot, M.L., and Schneider, M. 1987. Fiches FAO d'identification
des espèces pour les besoins de la peche. Mediterranée et mer Noire.
Zone de peche 37. Vol. II: 761-1530.
ISTPM, 1982. Rapport de mission sur l'évaluation des ressources halieutiques
de la marge continentale algérienne. Stocks pélagiques et stocks démersaux
exploitables au chalut . Campagne Thalassa, Ichthys, Joamy: 101 pp.
Whitehead, P.J.P., Bauchot, M.L., Hureau, J.C., Nielsen, J., and Tortonese, E.
1986. Fishes of the North-Atlantic and the Mediterranean, Ed. Unesco.
Vol. I: 683 pp.
Farid Hemida,
Laboratoire Halieutique, ISN-USTHB
BP 32 El Alia, Bab-Ezzouar 16.111
Algiers, Algeria
Fax : + 2 247913
e-mail: fhemida@hotmail.com
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