First Record of the Large-Scale Loach Paramisgurnus dabryanus (Cobitidae) in the United States

Abstract

Exotic species have been implicated as a major threat to native freshwater fish communities in the Unites States. The San Francisco Estuary watershed has been recognized as one of the most invaded systems where exotics often dominate the fish community. On October 6, 2014, members of the U.S. Fish and Wildlife Service detected a previously unknown exotic fish in a disconnected pool immediately upstream from the Chowchilla Bifurcation Structure in the San Joaquin River, a major tributary of the San Francisco Estuary. A member of the U.S. Fish and Wildlife Service initially identified the fish as an Oriental Weatherfish Misgurnus anguillicaudatus using external morphological characteristics. We conducted additional fish sampling near the Chowchilla Bifurcation Structure in November 2014 and collected a total of six additional specimens in disconnected pool habitats. Unexpectedly, genetic and meristic techniques revealed that these specimens were Large-Scale Loach Paramisgurnus dabryanus. To our knowledge this is the first confirmed occurrence of Large-Scale Loach in the United States and the suspected pathway of introduction is release from aquaria. Very little is known about the population in the San Joaquin River. We recommend further evaluation of the ecology, distribution, and abundance of Large-Scale Loach to better understand their potential impact on the fish communities of the San Joaquin River and the likelihood of establishment throughout the United States.

Fish Misidentification and Potential Implications to Monitoring Within the San Francisco Estuary, California

“…The use of preserved specimens rather than live fish may explain this dependency based on the possibility that the condition or appearance of specimens was altered to varying degrees during the freezing and defrosting process or the repeated handling by multiple observers. Lastly, we did not account for several of the DJFMP's fish-identification control measures, including bringing unidentifiable fish back to the laboratory for identification and confirming species identifications using genetic methods, which can greatly help reduce or eliminate species misidentification (Metcalf et al 2007;Teletchea 2009;Kirsch et al 2018). However, DJFMP observers rarely brought juvenile or adult fish from the field to the laboratory for species identification during our study period, with the exception of fishes of management concern being collected outside their known distribution.…”

“…; Hillman et al 1992;Moyle 2002;Beerkircher et al 2008Beerkircher et al , 2009) coupled with observer bias (e.g., level of experience and training; Fitzpatrick et al 2009;Shea et al 2011). Consequently, species misidentification has long been recognized as a potential issue when identifying small and inconspicuous fish (Ko et al 2013), new invaders (Kirsch et al 2018), fish underwater or by video (Griffith 1981;Hatch et al 1994), or when data are collected by resource users or volunteers Marko et al 2004;Garcia-Vazquez et al 2012). Although genetic techniques have been developed to improve fish species identification accuracy (Teletchea 2009), these techniques can be costly and difficult for large long-term monitoring programs to utilize, especially when large numbers of fish are being collected, fish are not being handled, or listed species are being collected and mortality, injury, or harassment is of concern.…”

Richard Francis Feeney (1954–2021)

“…Rick had a tremendous knowledge of eastern Pacific fishes and a keen awareness of how distributions were changing as oceans grow warmer, including sporadic records of fishes brought north by warm El Ni ño events. He went on to publish a number of new fish records (Feeney, 2006;Feeney et al, 2007;Gracian-Negrete et al, 2012;Lea, 2016, 2018;Kirsch et al, 2018), including collaborations with scientists in both North and South America.…”