WISE, J. P., AND C. W. Davis. 



1973. Seasonal distribution of tunas and billfishes in the 

 Atlantic. U.S. Dep. Commer., NOAA Tech. Rep. NMFS 

 SSRF-662, 24 p. 



Raymond E. Baglin, Jr. 



Southeast Fisheries Center Miami Laboratory 

 National Marine Fisheries Service, NOAA 

 75 Virginia Beach Drive 

 Miami. FL 33149 



RECORDS OF PISCIVORUS LEECHES 



(HIRUDINEA) FROM THE CENTRAL 



COLUMBIA RIVER, WASHINGTON STATE 



No records of leech infestations on fish of the Co- 

 lumbia River exist in the published literature. As 

 a whole, the freshwater hirudinean fauna of the 

 Pacific Northwest remains a relatively unsur- 

 veyed, little known, and neglected biotic group. 

 This is due, in part, to problems in leech identifica- 

 tion as well as in obtaining representative collec- 

 tions. 



We obtained leeches from the external surface, 

 oral cavity, and gill chambers of fish during a 

 continuing environmental assessment program 

 on the central Columbia River above Richland, 

 Wash. (Benton and Franklin Counties), from 1975 

 through 1977. This paper identifies four piscivo- 

 rous species, provides new host and distribution 

 records, and reviews some recent taxonomic 

 changes for the species encountered. Ecological 

 observations are included. 



The leeches recorded herein are Myzobdella 

 lugubris Leidy 1851, Piscicola salmositica Meyer 

 1946, Placobdella montifera Moore 1906, and Ac- 

 tinobdella inequiannulata Moore 1901. 



Methods and Site Description 



Fish were collected at monthly or bimonthly 

 intervals by a variety of gear (gill nets, trammel 

 nets, hoop nets, beach seines, and electroshocker) 

 from January 1975 to December 1977. Over 

 20,000 fish, representing nearly 40 species, were 

 examined during this period (Gray and Dauble 

 1977). Leech specimens were preserved in 10% 

 Formalin^ solution, either when captured or after 

 being examined alive in the laboratory. 



Our leech collections were more qualitative 

 than quantitative because leech-fish associations 

 in nature are normally periodic and facultative 

 despite the nutritional requirement of piscivorous 

 leeches for fish blood. Also, piscivorous leeches can 

 readily detach from fish captured by most types of 

 fishing gear, particularly from fish recovered 

 when moribund or dead. 



Occurrence of many freshwater leech species 

 can be correlated with characteristic aquatic 

 habitats. Water quality parameters vary season- 

 ally in the central Columbia River, as follows: 

 dissolved oxygen, 8.0-12.0 mg/1; pH, 7.4-8.6; phos- 

 phate (as PO4), 0.03-0.04 mg/1; ammonia- 

 nitrogen, 0.01-0.2 mg/1; hardness (Ca, Mg), 55-75 

 mg/1; and alkalinity (CaCOg), 50-67 mg/1. Water 

 temperatures range from 1° to 3°C in midwinter to 

 about 21°C in late August and early September. 

 There are no significant quantities of organic and 

 inorganic pollutants (our data). The water carries 

 minimal silt loads. 



The central Columbia River in the Hanford 

 Reach where our collections were made (river km 

 550-629) survives as the last free-flowing section 

 of the main channel above Bonneville Dam. Dec- 

 ades of hydroelectric development have trans- 

 formed other sections into a consecutive series of 

 river-run reservoirs. River flows in the study area 

 usually range from about 2,000 m^/s over much of 

 the year to over 12,000 m^/s during the annual 

 spring spate, when surplus runoff is passed down- 

 river over spillways from reservoirs (Nees and 

 Corley^). 



Additionally, Hanford flows are now regulated 

 at Priest Rapids Dam in response to daily and 

 weekly power demand peaks, causing water levels 

 in the river to fluctuate widely. This periodically 

 exposes and inundates a rocky or muddy shoreline 

 zone, apparently restricting development of a di- 

 verse leech fauna along the river margins. Water 

 levels in Wanapum Reservoir behind Priest 

 Rapids Dam (river km 639) and in Umatilla Res- 

 ervoir behind McNary Dam (river km 470) are 

 relatively stable, although subject to controlled 

 summer drawdowns. Substantial populations of 

 such common omnivorous leeches as Erpobdella 

 punctata (Leidy 1870), Helobdella stagnalis (Lin- 

 naeus 1758), and T/ieromjzon spp. occur along the 



'Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



^Nees, W. L., and J. P. Corley. 1974. Environmental sur- 

 veillance at Hanford for CY-1973. Unpubl. manuscr., 56 p. 

 R&D Rep., BNWL-1881, Battelle, Pacific Northwest 

 Laboratories, Richland, WA 99352. 



926 



FISHERY BULLETIN: VOL, 76, NO 4, 1979. 



