The Model Gtaf I-A High Speed Plaikton Sampler 



The following report is preliminary in nature and is presented 

 at this time, prior to comprehensive study, only to give other in- 

 vestigators an early opportunity to consider the possibilities of 

 the sampler described in connection with their own plankton-collecting 

 operations.) 



Realizing the limitations of conventional plankton-sampling gear, 

 a new type high-speed sampler was designed and constructed for col- 

 lecting operations of the Gulf Fishery Investigations, This sampler. 

 Model Gulf I, consisted essentially of a marine plywood body housing 

 a removable cylindrical wire-cloth plankton net with detachable 

 bucket, and a current meter. Although lost after the completion of 

 only six experimental tows averaging 3^ hours each, results seemed 

 to justify construction of a similar model. To insure greater ease 

 of handling at sea, to utilize a better current-measuring device, and 

 to incorporate improvements from observations made on the original 

 sampler, this new model was fabricated entirely of monel metal» 

 Superficially resembling the Scripps high-ppeed plankton collector 

 designed by John Isaacs, it differs markedly in many respects, 

 especially in operational procedure. 



During cruise 1-2 and a special cruise (N-2) of the Fish and 

 Wildlife Service research vessel Alaska , the new sampler was towed 

 62 times for a total of 202 hours or slightly more than 1800 miles. 

 Used with a l5-pound depressor, l/ the sampler towed true, and 

 according to wire-angle observations, with little variation in depth, 

 in spite of the rough weather encountered throughout most of 

 Cruise 1-2 and part of the special cruise. No difficulty was ex- 

 perienced in la\mching or retrieving the sampler while underway at 

 speeds up to ten knots. 



While detailed analysis has not been made, preliminaiy examina- 

 tion reveals that the samples obtained are composed of essentially the 

 same forms normally taken by conventional silk nets, and, with few 

 exceptions, the organisms are in surprisingly good condition. In 

 addition, a small number of larger, more agile animals were captured, 

 e.g., four Myctids 5»6, 3»8, 3»2, and 3»2 cm, in length, a 10,8 cm, 

 leptocephalus, an unidentified deep-sea fish measuring $,7 era., and 

 a squid 1,3 cm, in body length. 



]/ This depressor is the type developed by John Isaacs of Scripps 

 Institute of Oceanography, and is illustrated and discussed in 

 the California Cooperative Sardine Research Program Progress 

 JReport, 1950, on page 19, 



