ON THE DISPERSAL OF LOBSTER LARVAE INTO 

 THE EAST PACIFIC BARRIER (DECAPODA, PALINURIDEA) 



Martin W. Johnson ^ 



ABSTRACT 



The seaward drift of phyllosoma larvae of lobsters occurring along the coast and adjacent islands of the 

 eastern tropical Pacific Ocean was studied from plankton collections made jointly by the Scripps 

 Institution of Oceanography, Tuna Oceanography Research Program, and the National Marine 

 Fisheries Service, La JoUa, Calif. 



Numerous samples taken with trawl and plankton nets were made across the Equatorial current 

 system in two areas: lat. 15°N-5°S, long. 115°-125°W, and lat. 5°N-15°S, long. 95°-115°W. Many late 

 developmental stages of Panulirus penicillatus and P. gracilis and a fev/ Scyllarides astori were found, 

 all apparently having drifted mainly with the South Equatorial Current over a distance of 1,800 to 

 2,000 or more nautical miles from their likely origin, the Galapagos Islands or the coast of Central 

 America. A few larvae were found in the North Equatorial Countercurrent. This is at times a possible 

 route for return to the adult habitat, but it is doubtful that any of the larvae that have drifted to the 

 most western survey area will be returned by countercurrents in time for metamorphosis or that they 

 can successfully negotiate the remainder of the expanse of the East Pacific Barrier to reach the 

 mid-Pacific islands. 



The present report is essentially a follow-up of 

 a previous survey in which a large plankton 

 collection made by the multiship eastern tropi- 

 cal pacific (EASTROPAC) Project in 1967-68 

 was used in part to ascertain the systematics 

 and geographic distribution of the pelagic phyl- 

 losoma larvae of all of the spiny lobsters 

 (Palinuridae) and slipper lobsters (Scyllaridae) 

 known to inhabit the west coast and offshore is- 

 lands of Central America, Colombia, and 

 Ecuador (Johnson, 1971). In that survey an ex- 

 tensive area was covered along the coast and 

 seaward both north and south of the Equator to 

 about long. 126°W. It therefore forms the basic 

 groundwork drawn upon in the present report 

 dealing with the phyllosoma larvae taken dur- 

 ing a more restricted offshore survey within the 

 same area by the Scripps Tuna Oceanography 

 Research Program (STOR) in cooperation with 

 the National Marine Fisheries Service at La 

 Jolla, Calif., and Honolulu, Hawaii. This 

 offshore "skipjack survey" was designed and ini- 

 tiated in 1970 to study the migrations of young 

 skipjack tuna, Katsuwonus pelamis, in the east- 

 ern tropical Pacific Ocean (Williams, 1971, 1972). 

 A comprehensive review of the current system 

 and water masses so important to pelagic larvae 

 of the area is given by Wyrtki (1967). 

 From Point Conception southward to the Gulf 



'Scripps Institution ofOceanography, University of California 

 at San Diego, La Jolla, CA 92037. 



Manuscript accepted December 1973. 

 FISHERY BULLETIN: VOL. 72, NO. 3, 1974. 



of Guayaquil, Ecuador a total of four species of 

 palinurid and two species of scyllarid lobsters 

 occur. In the present survey only the larvae of 

 Panulir us penicillatus (Olivier, ISll) , P . gracilis 

 (Streets, 1871), P. inflatus (Bouvier, 1895), and 

 Scyllarides astori Holthuis, 1960 were found as 

 expatriate larvae from the coast or coastal is- 

 lands. Panulirus interruptus (Randall, 1840) oc- 

 curs off the coast of southern and Baja Califor- 

 nia, too far north for its larvae to be expected to 

 enter into the current system covered here ex- 

 cept as rare stragglers in the North Equatorial 

 Current. Evibacus princeps Smith, 1869 (the 

 second scyllarid) although common to the east- 

 ern tropical Pacific, apparently has a larval 

 period too short to be carried far from the coast 

 (Johnson, 1971). The larvae of P. gracilis and P. 

 inflatus are difficult to separate specifically if 

 the fourth pereiopods have been lost. However, 

 adults of only P. gracilis occur in the southern 

 range including the Galapagos Islands and all 

 but two larvae could be referred to that species. 

 The larvae of Jasus frontalis (H. Milne Ed- 

 wards, 1837) and Scyllarus delfini (Bouvier, 

 1909), the two lobsters found in the Juan Fer- 

 nandez Islands off Chile, were not found in the 

 equatorial currents or in the Peru Current to 

 lat. 24°S during the EASTROPAC survey and 

 none were taken in the present survey. 



The duration of the phyllosoma larval period 

 as derived from studies of different species in 



639 



