Effects of entanglement and escape from high-seas driftnets on rates of natural mortality of North Pacific albacore,

North Pacific albacore (Thunnus alalunga) are heavily fished and may have experienced recent reductions in recruitment (NOAA, 1991). U.S. troll fishery landmgs and catch per unit of effort (CPUE) have been decreasing since the 1960's and are currently a t only about 50% of their peak levels (Kleiber and Perrin, 1991; NOAA, 1991). Landings and CPUE by the Japanese pole-and-line fishery have also been falling continuously since the late 1970's'. North Pacific albacore are additionally targeted by longline fleets, and considerable numbers are taken by high-seas largeand small-mesh driftnet fleets. The small-mesh fleets of Japan, Taiwan, and Korea target neon flying squid (Ommastrephes bartramii) and incidentally capture albacore. The large-mesh fleets of Japan and Taiwan target albacore, skipjack tuna (Katsuwonus pelamis), and various billfishes (Istiophoridae and Xiphiidm). Foreign driftnet fleets and U.S. trollers taking albacore overlap geographically (Fig. 1). They also tar-

[1]  S. Mustafa,et al.  Condition indices and RNA : DNA ratio in overwintering European sea bass, Dicentrarchus labrax, in salt marshes along the Atlantic coast of France , 1991 .

[2]  David W. Willis,et al.  The Relative Weight Index in Fisheries Management: Status and Needs , 1991 .

[3]  J. Kitchell,et al.  Tuna Metabolic Rates Estimated from Energy Losses during Starvation , 1991, Physiological Zoology.

[4]  M. Ferguson,et al.  RNA/DNA ratios in white muscle as estimates of growth in rainbow trout held at different temperatures , 1990 .

[5]  M. Pawson.  Using otolith weight to age fish , 1990 .

[6]  R. S. Cone,et al.  The Need to Reconsider the Use of Condition Indices in Fishery Science , 1989 .

[7]  T. Bolger,et al.  The selection of suitable indices for the measurement and analysis of fish condition , 1989 .

[8]  G. Wedemeyer,et al.  Some potentials and limits of the leucocrit test as a fish health assessment method , 1983 .

[9]  J. G. Stanley,et al.  RNA-DNA ratio as an index to growth in salmonid fishes in the laboratory and in streams contaminated by carbaryl , 1983 .

[10]  M. Zeman,et al.  Seasonal variations in RNA–DNA ratios and in indicators of feeding, reproduction, energy storage, and condition in a population of bluegill, Lepomis macrochirus Rafinesque , 1981 .

[11]  D. McLeay,et al.  Leucocrit: A Simple Hematological Technique for Measuring Acute Stress in Salmonid Fish, Including Stressful Concentrations of Pulpmill Effluent , 1977 .

[12]  T. Haines.  An Evaluation of RNA–DNA Ratio as a Measure of Long-Term Growth in Fish Populations , 1973 .

[13]  P. C. Blaxhall,et al.  The haematological assessment of the health of freshwater fish , 1972 .

[14]  F. J. Bulow.  RNA–DNA Ratios as Indicators of Recent Growth Rates of a Fish , 1970 .

[15]  C. Perrin,et al.  Catckper-effort and Stock Status in the US . North Pacific Albacore Fishery : Reappraisal of Both , 2004 .

[16]  W. J. Fletcher.  A Test of the Relationship between Otolith Weight and Age for the Pilchard Sardinops neopilchardus , 1991 .

[17]  G. Wedemeyer,et al.  Stress and acclimation , 1990 .

[18]  G. Boehlert.  USING OBJECTIVE CRITERIA AND MULTIPLE REGRESSION MODELS FOR AGE DETERMINATION IN FISHES , 1985 .

[19]  R. C. Dotson.  II. – FAT DEPOSITION AND UTILIZATION IN ALBACORE , 1978 .

[20]  Richard N. Uchida,et al.  MODEL OF THE .MIGRATION OF ALBACORE IN THE NORTH PACIFIC OCEAN , 1962 .

[21]  W. C. Hutchison,et al.  The determination of nucleic acids in biological materials: an amendment , 1962 .

[22]  G. Markov,et al.  Substances interfering with spectrophotometric estimation of nucleic acids and their elimination by the two-wavelength method. , 1960, Biochimica et biophysica acta.