The IUCN/SSC Shark Specialist Group
Conversion Factors for Shark Fin to Shark Body Weight
The ratio most widely referred to in fisheries literature and used as the basis for most shark finning
regulations is 5% of wet fin weight to 95% 'dressed' (gutted and beheaded) carcass weight, or 2% of
wet fin weight to 98% whole shark ('round' or 'live') weight. This is the basis for the finning
legislation in the USA and possibly other states and Canadian Regulations. Other figures are, however,
occasionally quoted that give in a much higher fin ratio than the above. These discrepancies in
fin:body weight ratios seem likely to arise from differences in the ways in which fins are removed
from the carcass.
It is relatively common practice for fishers wishing to maximise fin weight (and hence, they assume,
the price paid for the fins) to leave significant quantities of flesh attached to the base of the fins.
This results in heavier fins, a lighter carcass and, therefore, much higher fin:carcass ratios.
Fin buyers subsequently trim excess flesh from the fins during preparation prior to export or sale
to processors. The drawback of this practice for the fishermen is that fin quality and unit price
is significantly reduced; tainting from the excess meat may even damage the valuable part of the fin.
Merchants and importers in East Asia also pay lower prices for such fins (the value/kg of fins imported
to Hong Kong, as reported by Hong Kong Customs, are lower for imports from Europe than elsewhere,
including the USA). Furthermore, the quality and value of the shark carcass is also significantly
reduced; this has led to the promotion of a whole shark landings policy by buyers and fishermen in
some Australian fisheries.
United States of America
The 5% fin: dressed carcass ratio is published in the Fishery Management Plan for Sharks of the
Atlantic Ocean (Anon. 1993). The original management measure to prohibit finning in Atlantic waters,
which was submitted for public consultation in the early 1990s, proposed to permit only five detached
fins (two pectorals, two dorsals and the caudal fin -excluding the lower value pelvic and anal fins)
to be landed with every finned shark carcass. Although the consultation undertaken (summarised in
section 9 of Appendix I, Anon. 1993) resulted in 'universal and strong support for a measure to
prohibit the wasteful practice of finning' some problems were identified with this proposal.
Comments included the following:
There are no recorded objections to the requirement to land carcasses and fins at the same time and
in the same place, in order to allow the regulation to be enforced. There were some industry objections
to a finning prohibition for dead sharks or sharks for which there was a limited market for the meat,
but these were over-ruled because "allowing this would cause a regulatory loophole making
enforcement of the general finning provision very difficult" (Anon. 1993).
- "The FMP's anti-finning measures should be based on a ratio by weight of total fins to
total carcasses landed because it would either allow landing more than 5 fins per carcass
or be easier to measure (ratio of two total weight measurements) while still preventing finning."
- "Some commenters objected to the proposed measure (5 fins per carcass landed) alleging that it
would not adequately prevent finning since it would allow mixing of large fins and small carcasses."
As a result of the consultation, "NMFS changed the finning measure to require that the total weight
of wet fins not exceed 5 percent of the total weight of dressed carcasses at point of first landing.
NMFS determined that the 5 percent by weight is appropriate and is supportable based on samples of
sharks dressed at sea under commercial fishing conditions. NMFS believes that the fins-to-carcass
weight ratio will be easier to enforce and will better prevent finning" (Anon. 1993).
The samples of 'sharks dressed at sea under commercial fishing conditions' refers to work
undertaken by the Narragansett Laboratory, reported in 1992, on board commercial target shark fishing
vessels. This examined the total wet fin weight and dressed carcass weight of 64 sharks from 12
species, and the total wet fin weight to whole (round/live) weight of 203 sharks from 21 species
taken by the commercial shark fishery in the Northwest Atlantic. The species examined in the
largest numbers were 60 blue sharks (from the single North Atlantic blue shark stock fished in
ICES areas), 48 sandbar, 33 shortfin mako, 33 scalloped hammerhead, 22 spinner, and 20 tiger.
Other species, including common thresher (5) were examined in smaller numbers. Although not the
most numerous, the most important commercial species in this fishery (high economic value and also
taken in large numbers) is the sandbar shark.
Table 1 presents the percentages of fin weight to whole (round) weight and dressed (carcass) weight
for the 21 species sampled on commercial shark fishing vessels during that study. This table is not
reproduced in full below; the extracts provided focus on the species sampled in largest numbers and
the less commonly sampled species also fished by the European fleet.
The sandbar shark, the most important commercial species in the US Northwest Atlantic shark fishery,
was also the species with the highest fin:carcass weight ratio, at 5.07% and fin:whole weight,
at 2.28%. The weighted average of all species taken was 3.65% fin:carcass weight and 1.69% fin:whole
weight. The ratio selected for the US Management Plan was, therefore, based on that for the sandbar
shark, the species with the largest fins caught in the fishery. This ensured that the new management
rule could not disadvantage any vessels engaged in the fishery that caught a large proportion of
sandbar sharks in their catches.
Observer data from the US East Coast bottom longline commercial shark fishery indicate that not only
has the 5% fin:carcass ratio has seldom been exceeded, it was only reached during two of the six years
for which data are available during 1994-2002. Annual fin landings during this period averaged 4.84%,
based on more than 33,000 landed fins and dressed carcasses of both large coastal and small coastal
sharks (George Burgess, University of Florida Commercial Shark Fishery Observer Program, personal
There does not appear to have been any debate upon whether a 5% ratio was appropriate during the
public consultation period prior to the enactment of the US Shark Finning Prohibition Act (2000),
which extended the measures in the Atlantic shark fishery management plan to all Federal waters of
the USA; comment was restricted to the method used to determine the ratio and resulted in agreement
that wet weight of fins was the favoured approach (Federal Register Vol. 67 No. 28, February 2002,
pp 6194-6202). (Dried fins are lighter and therefore represent a smaller proportion of carcass weight.)
Finning ("the practice of removal and retention of the fins but discarding of the carcass, then not
reporting the fins as landings... no shark carcass may be discarded at sea, with or without fins,
once it has been taken on board") became illegal in Canadian shark fisheries in 1994.
The 2001 Atlantic Fisheries Management plan states: "Fins from the commercial fishery may be sold,
traded or bartered (as a condition of licence) only in proper proportion to carcasses sold, traded
or bartered with a maximum of 5% by weight fins per dressed carcass weight. Fins may not be stored
aboard the vessel after associated carcasses are sold, traded or bartered and must be weighed and
monitored at the time of landing."
License conditions for the 2000 exploratory porbeagle fishery stipulate: "You may remove fins
from any shark you have retained. However, the weight of any fins so removed cannot exceed 5% of the
weight of the corresponding dressed shark carcasses you have retained. All shark fins and carcasses
must be unloaded at the same time, but weighed separately".
The conditions for the exploratory 2000 blue shark fishery stipulate: "You may remove fins from
any shark you have retained. However, the weight of any fins so removed cannot exceed 5% of the
weight of the corresponding dressed shark carcasses you have retained. All shark fins and carcasses
must be unloaded at the same time, but weighed separately."
These provisions are presumably based upon the ratio in force in the US fishery, rather than upon
species-specific ratios that have been developed specifically for these two species, although observer
data on fin ratios are held by DOF Canada and should be available (David Kulka, DOF Canada, personal
communication, April 2003).
A review of finning in Australian fisheries (Rose and McLoughlin 2001) used a comparison of fin export
and shark landings to determine that some 3900 t of shark were finned and discarded in Australian
fisheries in 1998/99. These appeared to be mainly blue sharks caught in tuna fisheries, with this
problem addressed on a temporary basis by amending permits for the Federally-managed tuna fisheries
to prevent the carriage or landing of shark fins not attached to a carcass. 'Whole shark' landings
(fins attached) were also required at that time in the States of Victoria, New South Wales, Western
Australia and Tasmania, with South Australia and Queensland in the process of developing similar
The authors reviewed several possible options for legislation to prohibit finning, including whole
shark landings and ratios of fins: carcasses, as in force in the USA. Fishers (20), fin buyers and
processors (7), fishing company representatives, wholesalers and scientific organisations were
interviewed during the course of the study. They found that "Various shark fishers within Australia
consider that for the species that they catch an average of wet fins:whole weight of 2%
is realistic" and that this agreed with the ratios provided in the US study (Anon 1993).
They also used an average figure of 5% for wet fin per dressed carcass weight, which was an
average of the ratios reported for species commonly taken in Australian waters (Galeorhinus
galeus, Mustelus antarcticus, Carcharhinus obscurus, Carcharhinus plumbeus and Prionace
glauca) as well as the value used in the USA.
A source document used in the Australian review which produced some significantly increased average
values for fin:carcass weight ratios was Gordievskaya (1973), see Table 3. Its publication pre-dates
the major increase in demand for shark fin that took place in the late 1980s (Cook 2000) and apparently
originated from a State (Israel) that is not known to have a significant shark fishery. It is
impossible to determine why the ratios reportedly presented in this document concur with those
for blacktip shark in Anon (1993), but not those for blue, silky and tiger shark, for which species
the ratios obtained from Gordievskaya (1973) are approximately three times higher. This document has
not been seen and the source(s) of the data it presents cannot, therefore, be confirmed. Until available
for review, these data, presented in Table 3, should not be used as the basis for the determination
of fin ratios for enactment in legislation.
The Draft Final Australian Shark Fisheries Management Plan (November 2002) notes that finning bans
were introduced in the Eastern, and Southern and Western, Tuna Fisheries in October 2000 and in the
Coral Sea Fishery in July 2002 and are under consideration in South Australia and other Queensland's
fisheries. Many of the Australian state finning bans arose as a result of buyer and processor
preference for receiving unfinned carcasses. The process of finning on board results in damage to the
carcass and wastage, particularly when fins are removed with significant quantities of meat still
attached. Buyer preference for whole landings subsequently became adopted as common fishing practice
and has since become enshrined in legislation (or proposed legislation) in some states (Terry Walker,
Fisheries Institute, Victoria, Australia, personal communication).
Anderson and Ahmed (1993) reviewed shark fishery statistics, including yields of fins from shark, for
the Maldives from three independent sets of data representing several separate surveys. Of these,
one set of data refers only to dried fin and is not, therefore, considered here. None of these surveys
sampled blue sharks, which are not taken in these tropical waters.
The largest data set documents weight of fins from 112 mostly large sharks caught during four
exploratory offshore finning surveys were removed with an 'L-cut' by a fin buyer and weighed prior
to sale. The average yield of wet fins:whole shark was 3.18 % (range 3.01-3.56%). The main species
involved was the silky shark (n=96), but the oceanic white tip shark (n=15) and one tiger shark were
also caught. Anon (1993) did not provide a fin:whole shark ratio for the oceanic whitetip, which has
among the largest fins of all pelagic sharks.
The third set of data was derived from a survey that collected 21 sharks of 8 species and a wide range
of sizes. Fins from these sharks were removed with a round cut (with meat on). As a result, the
ratios of fins:whole weight are considerably higher, averaging 4.5%. The species with the largest
fins was the oceanic whitetip, with one individual yielding a ratio of 8.3% of fins. Only four other
specimens of shark yielded over 5% of fin.
The difference between 'round cut' and 'L-cut' (also known as 'half-moon cut') is that the former
(round cut) is commonly used by fishermen interested in maximising the weight of fins by leaving
significant quantities of meat attached (on the assumption that this also maximises their profit).
The authors noted that "weight loss during trimming [by buyers] is substantial."
Another source of information on fin yields is Vanucchini (1999), but this FAO publication was not
available for review during the preparation of this document.
Implications for the European shark fishery
Sandbar sharks, the species with the largest fins reported from the US Atlantic shark fishery, are
landed in very small (unreported) quantities by the European fleet from ICES areas. The species
taken in significant numbers by the European fleet are: blue shark (fin:dressed carcass 3.74%,
fin:whole weight 2.06%), shortfin mako (4.22% and 1.68%), scalloped hammerhead (2.39% and 1.58%),
porbeagle (N/A and 2.19%) and thresher (N/A and 2.06%). Although no ratios are available for fin:carcass
for the last two species, their fin to whole weight ratios suggest that the former will also be less
than 5%; possibly even less than 4% using the methodology applied in the study cited above.
Because there is only a single North Atlantic blue shark stock, the fin ratios for this species
should be identical to those observed in the USA Northwest Atlantic fishery.
A likely explanation for any discrepancies between observations in the US shark fishery and those
elsewhere is that the latter are following the strategy described by Anderson and Ahmed (1993) to
maximise fin weight and hence profits. The assumption that heavier fins (because of attached meat)
leads to higher profits is not necessarily true, because fin buyers are likely to pay significantly
lower prices per kg for fins cut in this manner. They will then remove the meat by trimming to the
desired 'L-cut' before the fins are shipped. This is necessary because a poor cut that leaves residual
meat affects the odour and colour of the fin and can result in a fin of lower quality and value
(Subasinghe 1992, Rose 1996, cited in Rose and McLoughlin 2001). Indeed, when poorly trimmed fins
are retained on board for long periods before being landed for sale, tainting is likely to occur
and prices paid by buyers for this low quality product are likely to be much lower than for fins
that are properly trimmed when first removed from the carcass.
Poor trimming of fins will also reduce carcass quality. Australian shark buyers have, as noted
above, expressed a strong preference for purchasing carcasses with the fins still intact and pay
a premium for this product. This market preference has, with time, been transferred into fisheries
practice and subsequently into current or proposed finning legislation.
The policy, management, monitoring and scientific arguments in support of landing whole sharks
(fins attached), including the need for the collection of the species-specific and other quantitative
scientific data that are essential for monitoring catches and landings and implementing sustainable
shark fisheries management, are covered in more detail in a separate Shark Specialist Group briefing
document and not reviewed further here.
28 May 2003
Anderson, R.C. and Ahmed, H. 1993. The Shark Fisheries of the Maldives. Ministry of Fisheries and Agriculture, Republic of Maldives and Food and Agriculture Organization of the United Nations.
Anon. (1993) Fishery Management Plan for sharks of the Atlantic Ocean. National Marine Fisheries Service, National Oceanic and Atmospheric Administration United States Department of Commerce. Washington DC.
Cook S. (1990) Trends in shark fin markets: 1980s, 1990s and beyond Chondros 15.
Gordievskaya VS (1973) Shark flesh in the food industry. Israel Program for Scientific Transl. IPST Cat. No. 60080 2. CITED BY ROSE AND MCLOUGHLIN, BUT NOT SEEN.
Rose, C. and McLoughlin, K. 2001. Review of shark finning in Australian fisheries. Bureau of Rural Sciences, Canberra, Australia.
Rose DA (1996) An overview of world trade in sharks and other cartilaginous fishes TRAFFIC International 106pp.
Subasinghe S (1992) Shark Fin, Sea cucumber and Jellyfish: A Processors Guide. Infofish Technical Handbook 6. Infofish, Kuala Lumpur.
Vannuccini S (1999) Shark utilization, marketing and trade. FAO Fisheries Technical Paper 389. United Nations Food and Agricultural Organisation, Rome.
Examples of Shark Finning Regulations currently in force
The US Fishery Management Plan for Sharks of the Atlantic Ocean (1993) banned finning in US Atlantic federal waters from 3 to 200 miles offshore. The text states:
7.1.2 HARVEST RESTRICTIONS
The practice of finning is prohibited. Fins may be sold, traded, or bartered, but only in proper proportion to carcasses sold, traded, or bartered, with a maximum of 5 percent fins per dressed carcass weight. This percentage is based on the ratio of wet fin weight to dressed carcass weight for the sandbar shark (see Table 7.2). Fins may not be stored aboard the vessel after associated carcasses are sold, traded or bartered. All fins and carcasses must be weighed and sold at the point of first landing.
[The next section of the FMP (184.108.40.206 Release Condition) requires the live release of sharks that are not retained.]
The Shark Finning Prohibition Act (2000), (H.R. 5461, Public Law 106-557, 106th Congress) was intended 'to eliminate shark finning'. It addressed 'the problem comprehensively at both the national and international levels', extending the 5% ratio of wet weight of fins:dressed carcasses to all fisheries and fishing vessels in US federal waters (seaward of state waters) by an amendment to the Magnuson-Stevens Fishery Conservation and Management Act. No fins may be held on board or landed from any fishing vessel without the corresponding carcass weight being in possession or landed at the same time.
Most (if not all) US states have separate legislation controlling finning in state waters (0-3 miles) by restricting possession of a larger than 5% ratio of shark fins to shark carcasses; some (e.g. California, see below) have more stringent legislation.
Section 7704 of the California Fish and Game Code has, since January 1996, completely prohibited the removal of shark fins from any shark carcasses at sea, with one single exception: it permits the removal of the fins and tail of thresher sharks only, but a corresponding carcass must be in possession for each tail and fin, and all parts must be landed together. All other shark species must be transported and landed with the fins still attached. California manages shark fisheries out to 200 miles offshore, not simply within the usual 3-mile state territorial limits, and has important gillnet and line shark fisheries.
CALIFORNIA FISH AND GAME CODE
7704. (a) It is unlawful to cause or permit any deterioration or waste of any fish taken in the waters of this state, or brought into this state, or to take, receive or agree to receive more fish than can be used without deterioration, waste, or spoilage.
(b) Except as permitted by this code, it is unlawful to use any fish, or part thereof, except fish offal, in a reduction plant or by a reduction process.
(c) Except as permitted by this code or by regulation of the commission, it is unlawful to sell, purchase, deliver for commercial purposes, or possess on any commercial fishing vessel registered pursuant to Section 7881 any shark fin or shark tail or portion hereof that has been removed from the carcass. However, thresher shark tails and fins that have been removed from the carcass and whose original shape remain unaltered may be possessed on a registered commercial fishing vessel if the corresponding carcass is in possession for each tail and fin.
Australia: see text.
Costa Rica: The Costa Rican fishery authority INCOPESCA Board of Directors Agreement of February 2001 legally prohibits landing shark fins detached from carcasses.