EDWARDS and KLEIBER: NONRANDOMNESS ON LINE TRANSECT ESTIMATES OF DOLPHINS 



THE MODEL 



Model Structure 



This section presents a general description of 

 model structure. A detailed technical explana- 

 tion of the model can be found in Kleiber and 

 Edwards^ The model (TOPS: Tuna-vessel Ob- 

 server Progi'am Simulator) simulates the move- 

 ments of 75 tuna purse seiners and either 2,500 

 or 1,250 dolphin schools within a 1,200 x 1,200 

 square nautical mile area. Figure 1 provides a 

 gi-aphical comparison of the "study area" simu- 

 lated by the model, to the entire area within 

 which the tuna-dolphin association is exploited 

 by the purse seine fleet. Twenty-five hundred 

 dolphin schools is the nominal number of schools 

 expected within a 1,200 x 1,200 nmi area of the 



-■Kleiber, P. K., and E. F. Edwards. 1988. A model of 

 tuna vessel and dolphin school movement in the eastern trop- 

 ical Pacific Ocean: technical description of the model. 

 Admin. Rep. No. LJ -88-28. Southwest Fish. Cent., Natl. 

 Mar. Fish. Sen'., NOAA, LaJolla, CA. 



ETP, based on Holt's (1985,^'' 1987) estimates of 

 the total number of dolphins, average size of 

 dolphin schools, and species proportions for the 

 ETP, prorated from the entire ETP to an area 

 1,200 X 1,200 nmi. Simulations were also run 

 with half this number of schools to investigate 

 the ability of abundance estimates derived under 

 different conditions to reflect changes in actual 

 abundance in the model. Number of vessels is 

 based on reported size of the ETP purse seine 

 fleet, assuming about 50% of the fleet will be 

 fishing a given area of this size at any one time 

 (see lATTC Annual Reports 1983-87). 



All dolphin schools are assumed to be identical 

 (i.e., are replicates); all schools include only the 



""Holt, R. S. 1985. Estimates of abundance of dolphin 

 stocks taken incidentally in the eastern tropical Pacific yel- 

 lowfm fishery. Admin. Rep. No. LJ-85-16. Southwest 

 Fish. Cent., Natl. Mar. Fish. Serv., NOAA. LaJolla. CA. 



"Holt, R. S. 1985. Estimates of population size of dol- 

 phins in the eastern tropical Pacific using line transect 

 methods. Admin. Rep. No. LJ-85-20. Southwest Fish. 

 Cent., Natl. Mar. Fish. Serv., NOAA, LaJoUa, CA. 



160* M 155° W 150' H HS' U HO* U 135° «l 13o' M 125° H 120* M US' il 110° >l 105° d 100° >( 95° M 90° H 85° H 80° U 75° H 



FiGLRE 1. — Approximate e.xtent of the eastern tropical Pacific Ocean (ETP) tuna purse seine fishen-. Bo.xes enclose two areas 

 the size of the area simulated by TOPS (1,200 x 1,200 nmi), indicating relative sizes of the entire fishery area compared to the 

 area encompassed by the simulation. 



861 



