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Growth, mortality and recruitment of commercially important fishes and penaeid shrimps in Indonesian waters
189
last 10-15 years concerned with gene manipulation in micro-organisms has been almost overwhelming. Not only are these terms defined in this Dictionary of Microbiology and Molecular Biology, but the various synonyms employed for these terms are recorded and cross-referenced. This second edition of a Dictionary of Microbiology provides a welcome source of correlated and crossreferenced descriptions and explanations of the modern science of microbiology covering bacteriology, virology, mycology and protozoology. The system of cross-referencing used by the authors considerably extends the information available on any particular topic. There are 3 pages of notes for users of the Dictionary which enable one to obtain ready access to related information on any particular aspect of pure and applied microbiology. This dictionary will be of value as an initial reference work to undergraduate and post-graduate microbiologists, biochemists, molecular biologists and industrial chemists as well as to members of professions such as lawyers, engineers, accountants, media personnel, journalists, social workers, dentists, medical and veterinary practitioners, who may need to consider some unfamiliar aspect of microbiology or molecular biology in the course of their professional activity. Although it is about twice the bulk of the first edition, it is well bound and the print is clear if perhaps a little small. It is well priced at £69 (approximately US$137 ) by today's prices for such well-produced books. In reviewing the first edition in 1979, I commented that I expected it "to be a well-used and valued addition to my library" Over the last 9 years this prediction has proved to be abundantly true. I expect the second edition to be even more useful and valued for its wide and extensive coverage of modern microbiology and molecular biology. E.L. FRENCH Mt. Eliza Victoria Australia
INDONESIAN STOCK ASSESSMENTS
Growth, Mortality and Recruitment of Commercially Important Fishes and Penaeid Shrimps in Indonesian Waters. A. Dwiponggo, T. Hariati, S. Banon, M.L. Palomares and D. Pauly, ICLARM Technical Reports 17. Research Institute for Marine Fisheries, Jakarta, Indonesia and the International Center for Living Aquatic Resources Management, 1986, 91 pp., US$4.50 surface, $8.50 airmail, ISBN: 971-1022-26-5; ISSN: 0115-5547. This book exemplifies some of the benefits as well as some of the traps which the age of computers has brought to fish stock assessment. It has made it pos-
190 sible, by using sophisticated models and analytical techniques, to obtain estimates of almost all the key parameters from a minimum amount of data. However, this basis in limited kinds of data also results in there being little opportunity to examine the internal consistency of the system, and thus to obtain independent information as to the confidence which can be given to the results. The title describes exactly the results presented in the book. Estimates are given of the von Bertalanffy growth parameters (K, Lo~), total (Z), natural (M) and fishing (F) mortality rates, exploitation rate (E), and the selection and seasonal-recruitment patterns for some 51 data sets from 35 species offish in Indonesian waters. All the estimates are obtained from time series of length distributions by use of the ELEFAN series of computer programs developed by D. Pauly and his associates (Pauly et al., 1981 ). The estimates of M in the program, and hence those of F and E, are then obtained by applying the estimates of Lo~ and K in the relation between M and L~, K and water temperature proposed by Pauly ( 1980 ). For each stock the original length data are tabulated and a plate then presents histograms for these data with the estimated growth curves superimposed on them, the catch curve of log abundance against age calculated from these data, a plot of seasonal distribution of recruitment and histograms of probability of capture against length. The book also presents similar analyses for 9 data sets for the prawn (Penaeus merguiensis) in the Arafura Sea over the period 1969-1981. For these, the original data were weight distributions in the form of tails per pound. These have been converted into length distributions which are tabulated, but the process by which this has been done is not entirely clear, and the reference is to a PhD thesis in Indonesian. Recruitment and selection calculations have not been attempted because of these difficulties with the data. The presentation of the data and the various graphs constitute much the greater part of the book. Of the 91 pages only 6 are given to description of the data and the techniques, and about 3 (consisting largely of tables and figures ) to discussion of the results. The authors conclude that the average value of E for 24 demersal stocks on the north coast of central Java is 0.45, although which these are is not stated. On the basis of the Gulland rule-of-thumb that optimum E ~ 0.5, this is taken to imply that "the majority of species were exploited more or less optimally". The fact that a high degree of uncertainty attaches to many of the estimates is rightly pointed out. This is ascribed to the quality of the data, but there is no discussion of the range of the confidence limits of the estimates, or of the possibilities of bias. If biases in the estimates of L~ and K can occur, their results will flow right through the calculations to affect the estimates of E. This could affect the validity of the authors' belief that although little trust can be placed in the individual estimates the "general t r e n d s . . , will reflect the underlying reality". Some of the data sets, e.g. many of those for Clupeidae, show quite distinct
191 peaks which move with time and for these the growth estimates can give a subjective feeling of reasonableness. Others however, e.g. Carangidae, show such indistinct subsidiary peaks that one cannot avoid wondering what confidence can be given to the estimates of growth parameters and consequently to the conclusions as to exploitation rate. The prawn data show consistency in the estimates of L~ and K over the 9 data sets. T h e y also show, as presented, a good correlation between Z and fishing effort and, correspondingly, they fit quite well to Schaeffer and to Csirke and Caddy production models. The primary estimates of M are however obtained from the same L~, K, temperature function that is used for the fish species, but since this was derived solely from data on fish, and no evidence that it applies also to crustacea is adduced, the value of the estimates of M must therefore be open to considerable doubt. Other estimates of M are obtained from the relation, across samples, between estimated Z and catch sizes, but inspection of the figures suggests that in some of the critical years (e.g. 1969, 1976) the listed value of Z does not agree with the slopes of the catch curves. If the slopes are correct, M would seem to be considerably higher and E lower than is quoted. For both these reasons it seems that some doubt should attach to the conclusions as to the rate of exploitation of these stocks. The book is clearly important fbr anyone directly concerned with the fisheries of the Indonesian area. It is also likely to be useful to other workers with an interest in the multi-species fisheries of tropical areas. This is perhaps not so much for its analyses and conclusions as for the amount of data on the size distributions of a large number of species belonging to a wide range of families. These data could provide good background material for further studies on the modelling of exploited tropical fisheries. They have been drawn from many sources that would mostly be difficult, if not impossible, to access. The value of the book will be greatly enhanced when, as is promised, parallel data on catch and effort are also published. K. RADWAYALLEN 20/8 Waratah Street CronuUa N.S. W. 2230 Australia
REFERENCES Pauly, D., 1980. On the interrelationships between natural mortality, growth parameters and mean environmental temperature in 175 fish stocks. J. Cons. CIEM, 39 (2): 175-192. Pauly, D., David, N. and Ingles, J., 1980. ELEFAN 1: User's Instructions and Program Listings. pag. var. (mimeo). Pauly, D., David, N. and Ingles, J., 1981. ELEFAN II: User's Instructions and Program Listings. pag. var. (mimeo).
last 10-15 years concerned with gene manipulation in micro-organisms has been almost overwhelming. Not only are these terms defined in this Dictionary of Microbiology and Molecular Biology, but the various synonyms employed for these terms are recorded and cross-referenced. This second edition of a Dictionary of Microbiology provides a welcome source of correlated and crossreferenced descriptions and explanations of the modern science of microbiology covering bacteriology, virology, mycology and protozoology. The system of cross-referencing used by the authors considerably extends the information available on any particular topic. There are 3 pages of notes for users of the Dictionary which enable one to obtain ready access to related information on any particular aspect of pure and applied microbiology. This dictionary will be of value as an initial reference work to undergraduate and post-graduate microbiologists, biochemists, molecular biologists and industrial chemists as well as to members of professions such as lawyers, engineers, accountants, media personnel, journalists, social workers, dentists, medical and veterinary practitioners, who may need to consider some unfamiliar aspect of microbiology or molecular biology in the course of their professional activity. Although it is about twice the bulk of the first edition, it is well bound and the print is clear if perhaps a little small. It is well priced at £69 (approximately US$137 ) by today's prices for such well-produced books. In reviewing the first edition in 1979, I commented that I expected it "to be a well-used and valued addition to my library" Over the last 9 years this prediction has proved to be abundantly true. I expect the second edition to be even more useful and valued for its wide and extensive coverage of modern microbiology and molecular biology. E.L. FRENCH Mt. Eliza Victoria Australia
INDONESIAN STOCK ASSESSMENTS
Growth, Mortality and Recruitment of Commercially Important Fishes and Penaeid Shrimps in Indonesian Waters. A. Dwiponggo, T. Hariati, S. Banon, M.L. Palomares and D. Pauly, ICLARM Technical Reports 17. Research Institute for Marine Fisheries, Jakarta, Indonesia and the International Center for Living Aquatic Resources Management, 1986, 91 pp., US$4.50 surface, $8.50 airmail, ISBN: 971-1022-26-5; ISSN: 0115-5547. This book exemplifies some of the benefits as well as some of the traps which the age of computers has brought to fish stock assessment. It has made it pos-
190 sible, by using sophisticated models and analytical techniques, to obtain estimates of almost all the key parameters from a minimum amount of data. However, this basis in limited kinds of data also results in there being little opportunity to examine the internal consistency of the system, and thus to obtain independent information as to the confidence which can be given to the results. The title describes exactly the results presented in the book. Estimates are given of the von Bertalanffy growth parameters (K, Lo~), total (Z), natural (M) and fishing (F) mortality rates, exploitation rate (E), and the selection and seasonal-recruitment patterns for some 51 data sets from 35 species offish in Indonesian waters. All the estimates are obtained from time series of length distributions by use of the ELEFAN series of computer programs developed by D. Pauly and his associates (Pauly et al., 1981 ). The estimates of M in the program, and hence those of F and E, are then obtained by applying the estimates of Lo~ and K in the relation between M and L~, K and water temperature proposed by Pauly ( 1980 ). For each stock the original length data are tabulated and a plate then presents histograms for these data with the estimated growth curves superimposed on them, the catch curve of log abundance against age calculated from these data, a plot of seasonal distribution of recruitment and histograms of probability of capture against length. The book also presents similar analyses for 9 data sets for the prawn (Penaeus merguiensis) in the Arafura Sea over the period 1969-1981. For these, the original data were weight distributions in the form of tails per pound. These have been converted into length distributions which are tabulated, but the process by which this has been done is not entirely clear, and the reference is to a PhD thesis in Indonesian. Recruitment and selection calculations have not been attempted because of these difficulties with the data. The presentation of the data and the various graphs constitute much the greater part of the book. Of the 91 pages only 6 are given to description of the data and the techniques, and about 3 (consisting largely of tables and figures ) to discussion of the results. The authors conclude that the average value of E for 24 demersal stocks on the north coast of central Java is 0.45, although which these are is not stated. On the basis of the Gulland rule-of-thumb that optimum E ~ 0.5, this is taken to imply that "the majority of species were exploited more or less optimally". The fact that a high degree of uncertainty attaches to many of the estimates is rightly pointed out. This is ascribed to the quality of the data, but there is no discussion of the range of the confidence limits of the estimates, or of the possibilities of bias. If biases in the estimates of L~ and K can occur, their results will flow right through the calculations to affect the estimates of E. This could affect the validity of the authors' belief that although little trust can be placed in the individual estimates the "general t r e n d s . . , will reflect the underlying reality". Some of the data sets, e.g. many of those for Clupeidae, show quite distinct
191 peaks which move with time and for these the growth estimates can give a subjective feeling of reasonableness. Others however, e.g. Carangidae, show such indistinct subsidiary peaks that one cannot avoid wondering what confidence can be given to the estimates of growth parameters and consequently to the conclusions as to exploitation rate. The prawn data show consistency in the estimates of L~ and K over the 9 data sets. T h e y also show, as presented, a good correlation between Z and fishing effort and, correspondingly, they fit quite well to Schaeffer and to Csirke and Caddy production models. The primary estimates of M are however obtained from the same L~, K, temperature function that is used for the fish species, but since this was derived solely from data on fish, and no evidence that it applies also to crustacea is adduced, the value of the estimates of M must therefore be open to considerable doubt. Other estimates of M are obtained from the relation, across samples, between estimated Z and catch sizes, but inspection of the figures suggests that in some of the critical years (e.g. 1969, 1976) the listed value of Z does not agree with the slopes of the catch curves. If the slopes are correct, M would seem to be considerably higher and E lower than is quoted. For both these reasons it seems that some doubt should attach to the conclusions as to the rate of exploitation of these stocks. The book is clearly important fbr anyone directly concerned with the fisheries of the Indonesian area. It is also likely to be useful to other workers with an interest in the multi-species fisheries of tropical areas. This is perhaps not so much for its analyses and conclusions as for the amount of data on the size distributions of a large number of species belonging to a wide range of families. These data could provide good background material for further studies on the modelling of exploited tropical fisheries. They have been drawn from many sources that would mostly be difficult, if not impossible, to access. The value of the book will be greatly enhanced when, as is promised, parallel data on catch and effort are also published. K. RADWAYALLEN 20/8 Waratah Street CronuUa N.S. W. 2230 Australia
REFERENCES Pauly, D., 1980. On the interrelationships between natural mortality, growth parameters and mean environmental temperature in 175 fish stocks. J. Cons. CIEM, 39 (2): 175-192. Pauly, D., David, N. and Ingles, J., 1980. ELEFAN 1: User's Instructions and Program Listings. pag. var. (mimeo). Pauly, D., David, N. and Ingles, J., 1981. ELEFAN II: User's Instructions and Program Listings. pag. var. (mimeo).