SPC/Fisheries 24/WP 99
August 1992
SOUTH PACIFIC COMMISSION
TWENTY FOURTH REGIONAL TECHNICAL MEETING ON FISHERIES
(Noumea, New Caledonia, 3-7 August 1992)
SOME PROBLEMS ASSOCIATED WITH THE FREQUENT HANDLING OF TUNAS AND
THE IMPLICATIONS FOR THE FUTURE OF THE
REGIONAL TUNA TAGGING PROJECT
(Paper prepared by the secretariat)
INTRODUCTION
Tuna is one of the most important natural resources in the South Pacific and the
source of major revenues for some of the Pacific Island Nations (PINs). The importance of
the tuna resource is underscored by the creation in 1974 of the SPC Tuna Programme to
carry out research on tuna stocks, and in 1979 the Forum Fisheries Agency which was
charged with negotiating access to the resource by distant water fishing nations (DWFNs).
During the phase of the Regional Tuna Tagging Project (RTTP) over 100,000 tunas have
been tagged and released by the project fishing vessel, the Te Tautai. A huge volume of
data has been generated by these research cruises and preliminary results and conclusions
there-from have been presented at this and other meetings. It was during the course
of the earlier tagging project, the Skipjack Survey & Assessment Programme (SSAP) that
some curious gender related phenomena were associated with the frequent handling of tunas.
This was not followed up during the life of the SSAP but was noted in various internal
documents and unpublished manuscripts. During the RTTP, some effort was concentrated
following up on these earlier unpublished observations and these data and conclusions are
reported in the contribution.
SEX REVERSAL IN FISHES
Unlike mammals and birds fish may be hermaphrodites, that is have the ability to be
both male and female in the same body. Fish may be simultaneous hermaphrodites with both
male and female sexual organs (Rivulus spp and Serranus spp); protogynous
hermaphrodites, initially females transforming with age into males (Amphiprion spp)
or protandrous hermaphrodites, initially males transforming with age into females (eg Thalassoma
spp).
The method by which a fish makes this transformation is through the secretion of
hormones which have the effect of changing sexual organs and other secondary sexual
characteristics such as colour. The factors triggering transition are largely unknown but
Harrington (1967) demonstrated that environmental conditions, such as temperature,
crowding and starvation can greatly influence sexual transition in teleost fishes.
Recent evidence collected by the RTR now strongly suggests that skipjack tunas and
possibly yellowfin tunas go through a phase of sex reversal (see Figure
1). Further, unpublished biochemical studies at the AU Union Pacific Marine Research
Station at Smegma (near Vladivostok on the Russian Pacific coast) has shown that the site
of the secretion of the sex reversing hormone is in the outer epithelial layers of
skipjack skin (I. Kikdabollokov pers. comm.).
Research on the tuna sex reversal hormone by the Australian CSIRO (Mulligan &
Stropper 1992) has shown that this compound could also have similar effects on humans if
dosages were high enough, or if low level doses were administered over a sufficiently
lengthy time period. Mulligan & Stropper have also pointed out that the molecular
structure of the tuna sex reversal hormone means that it can be readily absorbed through
the skin.
EFFECTS OF HANDLING TUNAS OVER PROLONGED TIME PERIODS
The above research results naturally have direct bearing on the operations of the
RTTP. RTTP staff members tagging tuna are daily in contact with the skin of the fishes.
The highly potent and absorptive hormone is taken into the bodies of these unfortunate
individuals. That the frequent handling of tunas does have lead long term side effects is
now not in doubt. Figure 2 shows one of the RTTP cruise leaders
with a catch of skipjack somewhere in the South Pacific region. The cruise leaders
identity has been withheld to spare him/her any embarrassment, however, prior to the
transformation this individual was an 80 kg rugby playing, pipe smoking outdoors type
known affectionately to all and sundry as 'Butch'. Unfortunately, not all transformations
have been so fortuitous
Other less radical changes have been noted in RTTP staff, depending on the time these
individuals have spent tagging tuna on the Te Tautai. In its mildest form the influence of
the sex reversal hormone has lead to male staff showing a predilection for sewing and
crochet work, whilst more severe cases have revealed themselves through outlandish dress
sense and violent mood swings. In the case of the one female RTTP staff member who has
participated in tuna tagging on the Te Tautai there have been reliable reports of this
individual doing weightlifting and body building, showing a liking for beer and even
getting involved in bar room brawls. Thankfully, most of these reports show that this is a
temporary phenomenon if exposure is short lived and once contact with tuna ceases the
body's natural regulation of gender reverses the aberration.
IMPLICATIONS FOR THE RTTP
Clearly there are long term implications for the RTTP and the tuna programme if
tuna tagging is to continue. The Te Tautai is run more or less as an all-male ship. Where
staff are exposed in the long term to tuna sex reversal hormone, then there will need to
be some accommodation of this on the fishing boat. Ladies only rooms, toilets and showers
will need to be designated on the Te Tautai.
Further, an RTTP staff member who leaves Noumea as a Mister but comes back as a Miss
will need help adjusting to a new mode of existence through advice and counselling.
Amendments to the staff rules will be required, as will special compensation payments to
replace masculine wardrobes with female clothes. Those staff that are permanently affected
through exposure to tuna sex reversal hormone should be offered the chance of reversion to
their original gender through surgical means. The Eva Vestoff Medical Institute in Warsaw
is a world leader in the female to male transformation (strapadichtomy) but this is a
private institute and the operation and associated medical procedures are very expensive.
Similarly the leading exponent of male to female transformation, Dr Claud Balls, has
priced this operation known as a zobotomy at somewhere in the region of $100,000. Fund
raising exercises within the Tuna Programme and particularly the RTTP are going to have to
include a substantial sum to cover these medical expenses. Given the value of the tuna
resource to the region it is thought that such funding provision is entirely justified for
the staff of the tuna programme and the RTTP.
