5
34 EXPLOITATION OF POPULATIONS The following seven papers were delivered as a symposium on " The Exploitation of Populations" at the 1961 Conference. EXPLOITATION OF SEALS, WHALES AND PENGUINS IN NEW ZEALAND R. A. FALLA Dominion Museum, Wellington This summary of exploitation and assess- ment of its effects has been derived from consideration of (a) historical factors, (b) prcsent distribution and population levels, and (c) relevant features of the life history and ecology of the vertebrates concerned as far as this has a bearing on the exploitation results. In marshalling the known facts w~ end up with a summary which is about two- thirds history and one-third natural historv, an imbalance that brings out how little is yet known about the full life cycle and ecology of most marine vertebrates, at least in sufficient critical detail to allow an accur- ato estimation of exploitability. WHALES Exploitation of whales is considered in relation to (a) the southern right whale, (b) the sperm whale, (c) other whalebone whales, especially the humpback. (a) Right whale The destructive effects of exploitation in the case of right whales were rapid and severe becauso of the fact that this whale is the only one in the Southern Hemisphere which comes into very shallow coastal waters and bays for calving in mid-winter. The toll was thus taken directly on adult females with consequent loss of a high per- centage of calves. Even whaleships normally hunting far at sea found it profitable to anchor inshore during the calving season which extends through May, June and July, and thc joint onslaughts of a multi-national fleet and the resident shore-whalers in the period 1830-1840 brought the species to a point near extinction throughout the Southern Hemisphere. By the time shore whaling in New Zealand became uneconomic and there were alternative substitutes for the flexible baleen, right whale stocks were at a very low ebb. The right whale has never regained its former numbers, its breeding distribution is now more restricted than it was a century ago, but it would! appear to be stabilised at a lower level and annual sighting figures from Campbell Island indi- cate a slight and steady rise in numbers in that area. The species is now totally protected. (b) Sperm whale Exploitation of sperm whales has always been by pelagic hunting and the random drain on stock, especially of segregated groups of males, has never had a perman- ently disastrous effect. Economic 'considera- tions governed the intensity of hunting, and while sperm whales were still plentiful the gradual competition of petroleum products for illuminant oil and candles, and the loss of manpower attracted to gold 'rushes in California, Australia, and New Zealand in quick succession, caused the sperm whale fishery to dwindle. It was revived on a small scale 'based on Dunedin in the 1870s, but was more effective in providing an outlet for adventure and some good copy for writers like Frank Bullen than in promoting a busi- ness boom or reducing whales appreciably. Commercial interest in sperm whales has fluctuated ever since. Even under present-

EXPLOITATION OF SEALS, WHALES AND PENGUINS IN NEW … · WHALES Exploitation of whales isconsidered in relation to (a) the southern right whale, (b) the sperm whale, (c) other whalebone

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Page 1: EXPLOITATION OF SEALS, WHALES AND PENGUINS IN NEW … · WHALES Exploitation of whales isconsidered in relation to (a) the southern right whale, (b) the sperm whale, (c) other whalebone

34 EXPLOITATION OF POPULATIONS

The following seven papers were delivered as a symposium on" The Exploitation of Populations" at the 1961 Conference.

EXPLOITATION OF SEALS, WHALES AND PENGUINS IN

NEW ZEALAND

R. A. FALLA

Dominion Museum, Wellington

This summary of exploitation and assess-ment of its effects has been derived fromconsideration of (a) historical factors, (b)prcsent distribution and population levels,and (c) relevant features of the life historyand ecology of the vertebrates concerned asfar as this has a bearing on the exploitationresults. In marshalling the known facts w~end up with a summary which is about two-thirds history and one-third natural historv,an imbalance that brings out how little isyet known about the full life cycle andecology of most marine vertebrates, at leastin sufficient critical detail to allow an accur-ato estimation of exploitability.

WHALES

Exploitation of whales is considered inrelation to (a) the southern right whale,(b) the sperm whale, (c) other whalebonewhales, especially the humpback.

(a) Right whale

The destructive effects of exploitation inthe case of right whales were rapid andsevere becauso of the fact that this whale isthe only one in the Southern Hemispherewhich comes into very shallow coastalwaters and bays for calving in mid-winter.The toll was thus taken directly on adultfemales with consequent loss of a high per-centage of calves. Even whaleships normallyhunting far at sea found it profitable toanchor inshore during the calving seasonwhich extends through May, June and July,and thc joint onslaughts of a multi-national

fleet and the resident shore-whalers in theperiod 1830-1840 brought the species toa point near extinction throughout theSouthern Hemisphere. By the time shorewhaling in New Zealand became uneconomicand there were alternative substitutes forthe flexible baleen, right whale stocks wereat a very low ebb. The right whale has neverregained its former numbers, its breedingdistribution is now more restricted than itwas a century ago, but it would! appear tobe stabilised at a lower level and annualsighting figures from Campbell Island indi-cate a slight and steady rise in numbersin that area. The species is now totallyprotected.

(b) Sperm whale

Exploitation of sperm whales has alwaysbeen by pelagic hunting and the randomdrain on stock, especially of segregatedgroups of males, has never had a perman-ently disastrous effect. Economic 'considera-tions governed the intensity of hunting, andwhile sperm whales were still plentiful thegradual competition of petroleum productsfor illuminant oil and candles, and the lossof manpower attracted to gold 'rushes inCalifornia, Australia, and New Zealand inquick succession, caused the sperm whalefishery to dwindle. It was revived on a smallscale 'based on Dunedin in the 1870s, butwas more effective in providing an outlet foradventure and some good copy for writerslike Frank Bullen than in promoting a busi-ness boom or reducing whales appreciably.Commercial interest in sperm whales hasfluctuated ever since. Even under present-

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FALLA: SEALS, WHALES AND PENGUINS 35

day international regulation the species isnot regarded as in need of special protectio:1.It is caught regularly at some shore stations,but not in New Zealand where processingplants are small and not geared to deal withthe different grade of oil and by-productscharacteristic of sperm.

They are taken at the present time bymany factory ships proceeding south for theAntarctic season for baleen whales. Thisseason by agreed regulation now commenceslater than formerly, and the vessels fill intime hunting sperm en route. Without muchdiversion of course the combined fleets mayaccount for up to 5000 sperm whales in aseason.

(c) Humpback

This is the only baleen whale of currentcommercial significance in New Zealand,where it is, and has been, hunted from shorestations for nearly a century. Because of itsshort baleen it was ignored in the heydayof right whaling, nor was it easy to take withhand harpoon and lance. Migrating fromsummer feeding grounds in the AntarcticOcean to calving and pairing grounds in thetropics where they do not feed at all, hump-backs show a regular tendency to skirtcoastlines on both journeys. Furthermore,there have been shown to be several migrat-ing groups or populations with little or nointerchange between them though they arecontiguous at the Antarctic end of their trek.

In the early days of pelagic whaling fromfloating factory ships which did not com-mence its modern phase till 1923, theyformed a high proportion of the Antarcticcatch. This excessive drain caused a rapiddecline of numbers especially in the heavilyfished Atlantic sector, and international re-gulation eventually prohibited thc taking ofhumpbacks south of the 40th degree of southlatitude. This regulation placed no restric-tion on shore stations which have continuedto operate in South Africa, Australia, andNew Zealand, nor on the quaintly anachron-istic tropical hunting carried out by a familyunit in Tonga. Off the New Zealand coast,of course, the whales are travelling - north-bound from May till late July, and south-bound in October-November. Northernstations - formerly Whangamumu and laterGreat Barrier Island - found it profitable

to work both seasons, but the Tory Channelwhalers considered that not enough south-bound whales ever used Cook Strait to makea spring season worthwhile.

The catch at Tory Channel h,\s beenstudied and analysed almost every seasonsince 1946, a study that has been pnicticallythe single-handed (and self-impose!:!) taskof Mr. W. H. Dawbin, now of SydneyiUniver-sity. After 15 years the annual analysis stillfails to disclose any conclusive tr"nds ofdcclining stock though its age and sex com-position does show some change. Tqere hasbeen fluctuation of numbers, of coutse, andnone more spectacular than the presentseason 1961 just concluded. 1959 was a re-cord year with 207 whales in 73 days. 1960was another new record with 248 whales.1961, with no diminution of efficieqcy, hasproduced a mere 55 and the sea~on hasclosed. Great Barrier also has closed on atally of 20 (against an average of 7Q-80). Itis not necessary to postulate a drop ir; hump-back population, which is unlikely. A slightdiversion of route is a possibility, or evenan unexpectedly early passage, following aslight trend that has been noticed .for thepast five years. It should be added thitt thercis an untapped regular migration str'eam ofhumpbacks via the West Coast, convergingon land near the Southern Fiords and Fov-eaux Strait.

The New Zealand industry is small scalecompared with that of Australia or SouthAfrica, but continuation of the annual analy-sis is likely to make a significant cc)ntribu-tion to the solution of the problem of detect-ing danger points in exploitation.

(d) Other baleen whales

Blue, fin, and sei whales, the main quarryof the great pelagic whaling fleets, do notcome within the scope of this paper, but itis in this group that the greatest problemsof conservation are now posed. I know of nobetter simplified summary than W. H. Daw-bin's article "Whales and Whalij;rg" in"The Antarctic Today" (1952) which shouldbe consulted for its evaluation of the trendswhich may indicate over-killing - suchtrends as change between seasons.. in therelative numbers of the different sp~cies ofwhale, in the average length of each species,

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36 EXPLOITATION OF POPULATIONS

in the percentage immaturc, and in the catchper unit of eltort.

SEALS

In our consideration of seals, we come toa group of marine mammals which differfrom whales in that they are compelled tomake some rcgular contact with the shore,and this, of course, affects the intensity withwi1ic!1 tncy can be hunted. Distinction mustfirst be made between the kinds of seal in-volved in exploitation. These are (a) theNew Zealand fur seal, and to a lesser extentthe southern sea lion, both of which areeared seals, and (b) elephant seals.

(a) New Zealand fur seal

Singled out for thc value of its fur ando..If secondarily for its oil production, thefur seal was the earliest victim of intensive,a.ld largely indiscriminate, exploitationwithin the historic period we are consider~ing. Thc only regulation that ever operatedwas sharp decline of stocks, for the demandon world markcts for fur rarely showed anyfJuctuation. From declining prospccts inBass Strait, Australian sealcrs moved to NewZealand at the beginning of the 19th century,working gradually south from the Fiordlandand Stewart Island grounds to the relativelyunknown sub-Antarctic where, within thisperiod, several new islands were discovered.These discoverics were followed by an inten-sification of effort and a rapid decline inthe number of fur seals. In fact, the profit-able flush of hunting was over. in a littlemore than 10 years from the time of dis-covery of new grounds. Nevertheless, thereappcared to have becn only two localities inthis region where stocks were completelywiped out. Contemporaryaccounts creditedMacquarie Island and Antipodes Island withexclusivc possession of what was called theupland seal, and it is probable that thespecies concerned was, in fact, not the NewZealand fur scal which occupies the rest ofthe area and still survives in fair numbers.During a notable incrcase of numbers duringrecent years, it has appeared as far south asMacquarie Island. For the most part, theshore habitat of thc New Zealand fur seal isextrcmely rugged coastline. Most frequentlythe animals haul out on tumbles of largc

loose rocks at the base of eroding cliffs sothat approach from the shore meant negotia-tion ot clilts and approach from! seawardwas equalJy hazardous. The scal hei'ds underthcse conditions were both well hidden andextremely agile, and a certain l1l1mber ofanimals always escaped initial attacks. Asfur seals also have a certain amount of pela-gic movement which is wide ranging in thecase of immature animals, there werealways non-brccding rookeries as well as themore regular brccding rookcries. This meantthat by the time hunting had become unpro-fitable because of reduced numbers, therewas likely to bc still a fair nuclcu$ of stocksurviving. With a perceptible revival ofnumbers of seals in thc second half of the19th century, it was inevitable that' poachingshould take place. This went on in spite ofprotection afforded by law from about 1884,but this poaching does not appear to havebeen significant in its long-term effects. Openseasons between 1890 and 1946 were neverregarded as producing profitable returns,howcver, and the last open season in 1946was notable for the rathcr inept and unregu-lated hunting technique based largely on thetraditional indiscriminate approach. Therehas never been any cnlightencd policy whichwould permit exploitation and at! the sametims ensure the preservation of stock. Therehas been a very marked increase in thenumbcr of fur seals since 1946 and a con-siderable extension northward of their rcgu-lar range. Theoretically, enough is nowknown of fur seal biology from stuaies in theAlaska and Pribilov region of the North Paci-fic to permit rational exploitation. This isdone in the case of northern fur seals byestimating the number of immature maleanimals of certain age groups (usually 3and 4 years) that can bc taken safely. In thisnorthern region, however, the animals con-veniently segregated themselves on flat andaccessible islands and can be rounded upand penn cd almost like farm herds. Underthese conditions, the selective exploitationresults as is well known in a steady buildup in the numbers of the exploited herds.It would not be at all easy to apply thissystem to New Zealand. Here the breedingseason when pups are born, com'mences inDecember and at this time mainly old bulls,cows, and the growing pups are present onthe breeding rookeries. Here they rcmainuntil a partial dispcrsal commences in

I

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FALLA: SEALS, WHALES AND PENGUINS

March and the pups are finally weaned andindependent about August. Still wider dis-persal then commences and in the meantime,older age groups of the immature seals arewidely scattered forming semi-permanentrookeries which may, or may not, ultimatelybecome breeding places. Even if a surveydisclosed a definite pattern of distributionfor the age groups, it is unlikely that thetotal numbers that could be secured fromanyone age group would be sufficient formany years to maintain a financially profit-able industry. Nevertheless, if it is to beestablished it must start in an experimentaland subsidised way and with rational con-servation in view; the only condition underwhich it should be contemplated at all.

(b) Elephant seals

The range of these large earlcss seals isnow much further south than that of thefur seal, although overlapping. Breedingadults haul out about August, much earlierthan the fur seals, and they do so on mucheasier coastal terrain. It is unnecessary inthis paper to describe the well-documentedlife cycle and breeding habits. From the be-ginning of the historic sealing period, theseseals also were indiscriminately hunted fortheir oil which has maintained a high marketvalue up to the present day. Inevitably, since1810, they have suffered extreme depletionof breeding stock (for example, at Mac-quarie Island) to a point whcre huntingbecame unprofitable and the industry tem-porarily stopped. In spite of their greatervulnerability, elephant seals have shown re-markable capacity to re-establish. Possiblythe long pelagic life of the young animalsand their wandering propensities have beenthe main factors in promoting rapid build upof new populations in the old localities assoon as these were abandoned for a periodby the sealers or placed under conditionsof total protection. This is the condition nowobtaining in the whole of the New Zealandarea, and in Macquarie Island, which isunder Australian jurisdiction, as well. Thereare well-tested techniques worked out fromlong experience in the Falkland Island De-pendency region of the Atlantic Antarcticand elsewhere, and there is no doubt thatat Macquarie Island consideration could begiven to controlled or experimental exploita-tion. This is not to say that it should be

37

recommended for there are many factors toconsider, but merely to state that thc pro-position is practicable on the basis of pre-scnt population numbers and structure.

PENGUINS

Allowing for some differences in biologyand behaviour between mammals and birdsit is permissible to group at least one sectionof the order of penguins with seals as"essen-tially pelagic vertebrates using the lan~ onlyfor reproduction and moult. This section isexemplified by the sub-antarctic crestedpenguins which are represented in the NewZcaland region by five species, wherea~ everyother sector of the circumpolar zone hasbut two.

In prehistoric times it is probable thatone population of crested penguins .at theChatham Islands was exterminated by ruth-less predation of hunger-threatened Moriorisin the same inexorable fashion that ,sealedthe fate of the great auk in the northernhcmisphere. However, there is no real evi-dence except of the fact that they becameextinct there. In early European sealingtimes there was sporadic depredation oneggs and birds elsewhere in the sub-antarctic,but it was never sustained enough to haveany lasting effcct on the stock. Nor 'vas theshort period in which passing fashiOn tooka toll to provide skins for ladies' muffs. Ofmuch more significance for our stU<:lY wasthe sustained effort of the late Joseph Hatchwho sought to buffer the fluctuating for-tunes of elephant sealing with a much moreclcpendable exploitation of penguins "for oilat Macquarie Island. He did so with somesuccess for more than 25 years, weatherinEfinancial depression, loss of ships, and fre-quent litigation, but finally succumbing toorganised public opposition, backed by reso-lutions of scientific societies. The last straw,in contemporary opinion, was Hatch''; publicstatement that there were more royal pen-guins in the Nuggets rookery after 25 yearsof exploitation than when he started, andhe was branded a liar as well as a"'rogue.The ascertainable data from reliable sourcesover 40 years show that in fact he was right.

Hatch commenced his operations on kingpenguins, the largest but least numerous ofthe four species on Macquarie. They were al-

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38 EXPLOITATtON OF

ready much reduced by earlier sealer depre-dation, being more sedentary and vulnerable.Luckily tor the king penguins he found itdillicult to extract the oil uncontaminatedwith blood, and turned his attention to themore plentiful royal penguins, working onlyone convenient rookery at the Nuggets."When the hunters commenced work in

the spring they were engaged in procuringsea elephant oil, and did not molest the pen-guins coming ashore to breed. The penguin'season' began in February when the year-oldyoung or "tats" came out of the sea to moult.11 was from these birds that the first tollwas taken. Adults returning to the sea afterBesting were allowed to do so, as they alsotatteBed before coming out to moult inMarch, when a number of them were taken.The whole season was thus continuous forabout six weeks, and fat yearlings followedby fat adults were the victims. Whether byaccidcnt or design there was thus evolveda system of killing that inflicted a minimumof dau1age on the stock. So long as thenumber taken in a season did not exceed thepotential annual increase, such a systemcould continue indefinitely."The above paragraph is a quotation from

notes by E. R. Waite made in 1912 (Falla1937, p. III). Since then, as a result of ashort field study of the Nuggets rookery inDecember 1930 (ten years after the closingof Hatch's operations) and a further visitin December 1957, I would go further thanWaite in considering that there is evidencethat the breeding colony was actually ex-panding in size at that time in spite of thefact that the industry's toll was up to 150,000birds per season.Some of the relevant records of the size

of Nuggets rookery given chronologicallyare:-(a) J. 1. Thomson in 1879 "made a rough

estimate of the acreage, and of thenumber of penguins to the square yard,and concluded that there were in sightno less than 180,000."

(b) Ainsworth in 1912 estimated the totalarea covered by the breeding groups asapproximately ten acres and secured avaluable photograph which shows maxi-mum extension of area (greater thanany recorded since) and a density con-sistent with a population of 500,000birds (estimate by Blake). He also re-cords the independent conclusion that

POPULATIONS

"the yearly increase in numbers in theonly rookeries that are being workedis certainly greater than the depreda-tions due to the sealers."

( c) In December 1930 the cleared areas stilltotalled about 10 acres, but the densityseemed less than in Ainsworth's photo-graph and our (B.A.N.Z.A.R.E.) esti-mate was of 338,800 breeding birds.

(d) By December 1957 the breeding popula-tion seemed stabilised at a lower level,vegetation has re-covered perhaps threeacres of the formcr cleared areas. On thebasis of earlier estimation methods thebreeding total would be about 250,000birds, half the number present in 1912.

No far-reaching conclusions need beclaimcd to follow this record of fluctuations,for other factors were no doubt involved.At present, while Nuggets now declines,other new colonies of royals elsewhere onMacquarie are increasing. The relevant pointis that Nuggets reached its peak late in aperiod of 25 years of exploitation, and doubt-less for reasons comparable with those thatstimulate population growth in the scienti-fically exploited populations of Alaska furseals.

GENERAL CONCLUSIONS

(a) All pelagic vertebrates (whales, seals,or birds) are vulnerable if exploitationinterferes regularly with critical periodsin the breeding cycle. The near-extinc-tion of right whales in both hemispheresis a reflection of this fact.

(b) Selective culling of age groups whichhave been found by study and calcula-tion to be "expendable" may stimulatean actual rise in total breeding stock,as exemplified in the controlled exploit-ation of some seals and penguins.

(c) The only sure scientific check on theeffects of exploitation is a c<>mbinationof full biological data with an analysisof statistical data aimed at revealingthe population dynamics of the stock.On an international scale this is nowbeing attempted with baleen whales.

REFERENCES

DAWBIN,W. H., 1960. The composition of the NewZealand whale catch in 1959. Norsk Hval-.fangst-Tidende 9 :401-409.

FALLA,R. A., 1937. Birds. B.A.N.Z.A.R.E. Rep. Ser. B2 :1-304.