(from "Report of the Scientific Committee", 1960 meeting)

34. The terms of reference given by the Commission to the Ad Hoc Scientific Committee meeting as a Workshop, whilst directly mentioning availability of data, methods of biological research and of measurement of effort, and programmes of field collection, directed attention to the use of methods of research into the dynamics of populations. The terms of reference of the Committee of Three related expressly to the methods used in studies of population dynamics. The reports of these two bodies disclose that the meeting at Rome gave research workers an opportunity of examining the applicability of more advanced population research methods to stocks of whales, and led to the formulation of plans for vigorous action to make use of these methods. When successful these methods enable research workers: (1) to present an accurate assessment of the condition of the stock under investigation, (2) to make a prognosis of the consequences of various courses of action with regard to exploitation of the stock, and (3) to indicate ways in which a sustained yield may be obtained; moreover, it is possible to indicate how a sustained yield may be brought to an optimum.

35. The Committee believe that these results could be obtained with regard to whale stocks but, as shown in the reports from the Rome meeting, much work has yet to be done to assemble all data now in the hands of research workers and to submit these data to the necessary procedures of analysis and interpretation. It is absolutely necessary that the work proposed in the report of the Rome meeting should be carried through with the utmost speed and when this is done the Committee will be in a position to furnish the Commission with more accurate advice on which to formulate regulations for the rational conduct of whaling operations.

36. Pending the development of this work the Committee must continue to resort to the rather qualitative indexes they have employed in the past, and the observations which follow, on the present situation, are made in this sense. However, before making these observations it wishes to draw the attention of the Commission to certain generalisations, proper to the general theory of populations, that have a relevance to the investigation and regulation of whale stocks. Acceptance of these generalisations is unavoidable and does not depend upon the completion of the studies planned at the Rome meeting.

37. A. Each independent stock should as far as possible be analysed and assessed separately; predictions should be made separately for each stock, and regulatory measures should be so formed that the kind and intensity of exploitation to which each stock is subject is appropriate to its properties.

38. The "independence of a stock" refers to its being self-contained with regard to reproduction and to its response to forces repressing it or permitting its expansion. This generalisation has several consequences. First, it means for research that an early task is to identify the stocks and to define as closely as possible the limits of distribution of each in time and space; marking operations are virtually indispensable for this. It further means that every effort must be made to organise the keeping of records of whaling operations and of biological sampling so as to be able to segregate data relating to each stock. Secondly, it follows from this generalisation that regulatory measures framed for several stocks simultaneously (whether of a single species or not) are likely to be ineffective and might even fail completely. For example, setting a limit to the total catch to be taken from several stocks, without setting a limit for each stock separately, may result in a progressive exhaustion of one stock after another. This is because the fishing mortality induced by the total catch, which might not be excessive to any one of them if evenly shared among them, might prove to be quite destructive when brought to bear upon one alone. This result is likely to occur where a preference exists among the stocks. Setting an overall limit is likely to give a false sense of security.

39. B. Regulatory measures should be framed in the light of evidence on all the relevant characteristics of the stock, even though each regulation may relate to only a single characteristic, such as the age at attainment of maturity.

40. The consequence of this is to suggest that the validity of the regulations at present in existence, since they were framed without the benefit of a full account of the stock, may be called into question. However, as is shown in the next generalisation, approximate measures sometimes have to be adopted temporarily to provide some restraint on catching in situations where provisional indexes show with reasonable certainty that the level of exploitation is greater than the stock can sustain. In particular the Committee refer to the existing set of legal minimum lengths for which the main argument, at the time they were established, was that they were near to the average length at attainment of maturity. The setting of a legal minimum length simply with regard to average size at attainment of maturity could be more rigorous than necessary, or could be quite insufficient; the methods of population analysis could provide estimates of the yield to be obtained from a given stock at various legal minimum lengths. Nevertheless, in the present situation there is little doubt that most whale stocks are subject to excessive fishing mortality and consequently, regardless of their appropriateness, to reduce any of the various legal minimum lengths would only be to increase the fishing mortality and further to reduce the stocks.

41. C. Although the direct information on the size and characteristics of stocks that methods of population analysis can provide, constitutes the best basis on which to frame a positive system of regulation, in the absence of such analysis various secondary indexes of the condition of the stocks give a valid basis for interim restraining measures.

42. The confidence to be placed in such evidence will increase with the number of such indexes available and with the agreement they show. Changes in catch per unit effort, in average length or age, and in certain compositional characteristics of the catch, are among the more important of these indexes.

43. Formulation of the foregoing generalisations at this juncture was necessary because the Committee are called upon to comment on several matters for which they need the results of population studies to be able to make an effective answer. The observations they can make at this time will, they hope, be seen in proper perspective in the light of the foregoing generalisations.

Condition of Stocks
44. (a) Blue Whale: Although the total 1960/61 catch of Blue whales was higher than that of any of the preceding five years, a large proportion of it consisted of pigmy blue whales taken by Japanese expeditions in an area farther north than in former years; the same apparently was true of the 1959/60 catch, and hence it is found that the blue whale catch (apart from the pigmy blue whales) continues uninterruptedly its downwards trend. Associated with this index are several other lines of evidence which indicate that the stocks of this species are being given no opportunity of regeneration, and hence that continued fishing of them at the present level of effort will result in progressively lower catches. For these reasons the Committee wish to reiterate the views expressed last year, namely that blue whales need total protection for a period.

45. (b) Fin Whale: The total 1960/61 catch of this species was slightly higher than that of preceding years. However, several indications have been given that a downward trend in the abundance of this species has been initiated, as noted in paragraph 11 of the Committee's report to the Twelfth Meeting in 1960. It is clear that unless some restraint is placed on exploitation the trend referred to will continue and catches will begin to fall; this fall could be deferred by increases in effort but these would only steepen the trend and accelerate the process.

46. (c) Humpback Whale: The Committee comment as follows on each of the six southern humpback groups in the light of such knowledge or evidence as they have:-

47. With regard to Group I (South East Pacific), there is no evidence of a decline in the population. It is one which has not been long hunted, but it is likely to be a rather small stock. No recommendations are made.

48. Group II (Atlantic region) has been hunted since the beginning of Antarctic whaling, and the stocks are severely reduced. The Committee feel sure that it would be best to maintain complete protection of the populations in this region.

49. In Group III also (West Indian Ocean) the stock has been much reduced. Although no new restrictions are suggested, it is important that no additional taxation should be initiated.

50. The 1960/61 catch from the Group IV (East Indian Ocean) stock of this species was still lower than that of preceding years. Evidence on intensification of effort and on composition of catch indicates that the stock has been grossly reduced to a level at which catching, continued, could be sustained at only a very low level - say, between one and two hundred from the entire group (i.e., from West Australia and Antarctic Area IV); any greater catch can only further aggravate the situation.

51. The 1960/61 catch from the Group V (South West Pacific) stock of this species more or less maintained the level of preceding years but on the Australian coast the catch per unit effort fell severely, and this, with evidence on catch composition, indicates that the total taxation of this stock has been excessive. There are grounds for considering that this stock is of a magnitude to give a sustained yield not exceeding one thousand; if this should prove to be true it will be advisable to adopt measures to ensure that this limit is not exceeded.

52. The hunting of whales in Antarctic Area VI (Central Pacific) is only a recent development. There is some evidence to suggest that what has been regarded as a distinct Group VI stock is in fact only part of Group V; if this should be confirmed by marking, the designation of 'Group VI' should be discontinued, and any measures adopted for Group V should be extended eastwards.

53. (d) Sei Whale: The increase in the Antarctic catch of sei whales was noted. There is at present no information on the condition of the sei whale stock. More marking and research on the general biology of this species is needed.

54. (e) Sperm Whale: The only evidence on the status of the stocks is a progressive decline in length of those taken in the Antarctic.

_