Hello form New Zealand
May this help with your doubts? Or confuse them more...
As swordfish has sexual dimorphism (males are smaller). I can sent you info
on how to differentiate them on board during gutting if you like...
Doubt there would be linking info to Mercury content in the normal
bibliography, because bioaccumulation rates are variable with species
predated and residency time of the stocks in a particular area... And growth
rates differ as per locations...
For example, Swordfish found in the New Zealand EEZ are part of a much
larger stock that spawns in the tropical central to western Pacific Ocean.
Within the EEZ, most swordfish are caught when sea surface temperatures are
17º to 19º C. Their residence time in the EEZ and adjacent waters is
unknown.
Growth rates of adult male and female swordfish differ in the Pacific
(Uchiyama et al., 1998), as elsewhere (Ehrhardt et al., 1996). Grigs and
Richarson (2005) report that in NZ waters females are caught about three
times as frequently as males in the longline fishery, and are 125 cm (lower
jaw to fork) in length and longer in size.
Swordfish size varies with latitude in the EEZ, with larger swordfish (and
hence more females) caught south of 40º S. Average length (lower jaw to fork
length) of swordfish caught in the EEZ has been relatively stable since
1991, averaging 195 cm for the charter fleet and 162 cm for the domestic
owned and operated fleet (based on limited observer data). Males are
substantially smaller than females with most males smaller than 189 cm (80%)
while most females (53%) are larger than 189 cm for the combined domestic
and charter fleets. (Anon. 2004)
References that may help
Anonymous (2004) http:// www.fish.govt.nz/sustainability/
research/stock/w97docs/swo_04.doc
Ehrhardt, N. M., R. J. Robbins, and F. Arocha. 1996. Age validation and
growth of swordfish, Xiphiasgladdius, in the Northwest Atlantic. Int. Comm.
Conserv. Atl. Tunas, Coll. Vol. Sci. Pap., vol. 45(2):358-367.
Griggs, L.H.; Richardson, K. (2005). New Zealand tuna fisheries, 2001 and
2002. New Zealand Fisheries Assessment Report 2005/4. 58p.
Uchiyama, J. H., R. A. Skillman, J. D. Sampaga, and E. E. DeMartini. 1998. A
preliminary assessment of the use of hard parts to age central Pacific
swordfish, Xiphias gladius. In Biology and fisheries of swordfish, Xiphias
gladius (I. Barrett, O. Sosa-Nishizaki, and N. Bartoo, eds.), p. 261-273.
U.S. Dep. Commer., NOAA Tech. Rep. NMFS 142.
Regards
-- Francisco Blaha www.franciscoblaha.comOn 22/11/05 4:28 pm, "Angela Thornton" <indyattic@yahoo.com> wrote:
> > I have seen some conflicting information regarding the > reproductive age of swordfish and am hoping for > accurate information or at least a consensus. > > Is there a size of swordfish that has reached sexual > maturity and is still likely to test below 1ppm for > mercury? > > The fish that I have seen tested the most have been > out of the Caribbean and Pacific coast of South > America. Most of the time if these fish are under 120 > lbs. (H & G) they will test under 1 ppm. > Do you think that fish this size will likely have > reproduced yet? > Will fish from the Atlantic and Asian Pacific water > test similarly for mercury? > > Thanks, > > Angela Thornton > > "It's the plumber. He's come to fix the sink." > > __________________________________________________ > Do You Yahoo!? > Tired of spam? Yahoo! Mail has the best spam protection around > http://mail.yahoo.com >
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