The IUCN/SSC Shark Specialist Group
Shark News 7: June 1996
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News
Reproduction in the whale shark
Joung et al. (1995) have recently provided the first firm evidence of
ovoviviparity in the whale shark Rhyncodon typus, based on the
dissection of a 7-8 m, 16,000 kg female harpooned in the eastern
waters of Taiwan in July 1995. Although previous literature on the
species has considered this type of reproductive strategy likely, the
unexpected aspect of this report is that about 300 embryos were
revealed in the uteri. Several size classes were present, suggesting a
long breeding season. Most embryos were in eggcases with yolk sac,
but the largest (60-65 cm TL), presumably virtually full term, were
outside their eggcases. Some of these survived dissection and transfer
to aquaria. A report of these observations will also be presented at the
New Orleans American Elasmobranch Society Meeting in June 1996.
Joung, S.J., et. al. December 1995. Ovoviviparous whale shark.
(Abstract of Symposium paper, Tokyo, November 1995.) Report of
the Japanese Society for Elasmobranch Studies, 32, p.32.
Sawfish in the Mekong River
Shark Specialist Group member Tyson Roberts has drawn the editor's
attention to reports of sawfish in a 1993-1994 study of fisheries in
southern Laos and north-eastern Cambodia. Roberts and Warren
(1994) note that sawfish (likely Pristis microdon and/or P.clavata)
caused considerable damage to gillnets and were occasionally caught
as recently as ten years ago just below the Lee Pee Waterfalls, Laos.
One fisherman used to see two or three of up to 10 kg in weight in
February-March each year, presumably following other migratory
fish. Sawfish are now absent or very rare in the Great Lake of Tonle
Sap; the most recent known capture was 40 years ago. One Pristis was
reported landed at Ban Wernkam towards the end of 1993. Overall,
the 1993/94 season was the worst ever experienced by local fishermen,
representative of a long-term basinwide decline of Mekong fisheries,
where gillnets are intensively used.
Roberts, T.R., and Warren, T.J. 1994. Observation on fishes and
fisheries in southern Laos and northeastern Cambodia, October 1993-
February 1994. Nat. Hist. Bull. Siam Soc. 42: 87-115.
Proposals for protection of sharks in Australia
The Australian Nature Conservation Agency has recently received a
nomination for protection of the white shark Carcharodon carcharias
and the grey nurse shark Carcharias taurus under the Endangered
Species Protection Act. The grey nurse is already protected in New
South Wales, and the white shark protected in Tasmanian waters and
proposed for protection in South Australia, but listing under the
Endangered Species Protection Act would have the effect of protecting
these species throughout commonwealth waters. The federal
government will also be required to consult states and territories to
develop and provide funds for national recovery plans for the species.
Sharks were noted as being potentially vulnerable in Australia's
first State of the Marine Environment report, released last year. The
whale shark has recently received protection in Western Australia.
Sharks highlighted in UK biodiversity report
The basking shark Cetorhinus maximus, tope Galeorhinus galeus,
porbeagle Lamna nasus and blue shark Prionace glauca have all been
listed in the recently published UK Steering Group Biodiversity Report
Meeting the Rio Challenge. They appear on a long list of some 1,250
species which are considered to be of conservation concern (however,
this is not considered to be a comprehensive listing). The report
notes that monitoring of these species is important in establishing
a review of the health of biodiversity in the UK, and should take
place within five years.
The Marine Stewardship Council initiative
A major new initiative to halt the serious decline in global fish stocks
was announced in February by WWF International and Unilever Plc/
NV, one of the world's largest buyers of frozen fish. They have agreed
to create a Marine Stewardship Council (MSC) following a wide-ranging
consultation of all those involved with fisheries (from scientists
to regulators and environmentalists).
The MSC will be a wholly-independent body, setting out the
broad principles of sustainable fishing and laying down specific
standards for individual fisheries. Products made from fish caught in
accordance with these standards will receive an MSC 'on-pack' logo.
This will allow consumers to select fish products that come from a
source certified as sustainable. Not only should this approach enable
declining commercial stocks to recover, with associated benefits for
the marine environment, but it should also help coastal communities
dependent on fishing to avoid economic and social collapse.
The aim is for the MSC to adopt a similar approach to that which
has successfully promoted sustainable forestry; uniting the efforts of
industry and the consumer to promote market-led incentives for
sustainable fishing. This approach seems more likely to succeed than
the repeatedly unsuccessful political efforts to tackle the problem of
declining fish stocks (e.g. by setting catch quotas and other regulations).
Conservation of chondrichthyans in the Maldives
1995 was an important year for shark and ray conservation in the
Maldives, with a number of new regulations coming into effect.
Whale sharks Rhincodon typus have been protected under the
Fisheries Law which prevents the catch of all types of bodu mas (a
local term for true whales and other large 'fish' including whale
sharks). However, this term is ambiguous; some consider it refers to
true whales only. A couple of whale sharks were reportedly caught in
1994 for their liver oil and/or fins, both of which commodities are of
very low value in this species. Whale sharks are recognised as a
significant attraction for tourist divers. The Ministry of Fisheries and
Agriculture announced a specific regulation in June 1995, banning all
fishing for whale sharks, to reinforce the existing Law.
Rays, particularly manta rays (Mobulidae) and stingrays
(Dasyatididae) are a major attraction for tourist divers in the Maldives.
There is a small traditional and sustainable catch for rays for their skins
(used on drums), oil and shark bait. However, any increase in fishing
effort to support an export fishery would likely prove non-sustainable,
damaging both traditional users and the tourism sector. To forestall
and avoid such problems, the Fisheries Ministry banned export of rays
from June 1995, and of ray skins from 1 January 1996.
On World Environment Day (5 June) 1995, the Ministry of
Planning Human Resources and Environment declared 15 top diving
sites as Marine Protected Areas. Nine of these are or were famous for
their sharks, but there have over the years been a number of incidences
of fishermen catching sharks at these sites. Since a grey reef shark
Carcharhinus amblyrhynchos may be worth up to 1,000 times more
alive as a source of diving revenue than dead on a fishing boat, it
makes sense to protect sharks within tourism zones.
Although these regulations provide significant protection for some
chondrichthyan fishes in the Maldives, there is a need for further action.
For example, reef sharks are not confined to particular reefs and, in the
Maldives at least, do show some seasonal migratory behaviour associated
with the changing monsoons. Therefore, protecting particular dive sites
will not give these sharks complete protection. Plans are therefore being
considered to protect more dive sites as well as much larger reef areas
where tourism development is concentrated.
R. Charles Anderson and Maizan Hassan Maniku, Marine
Research Section, Ministry of Fisheries and Agriculture, Malé,
Republic of Maldives.
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