Friends of the Upper Mississippi

The end of the summer growing season is a busy time for the mussel program. As water temperatures begin to drop, propagated juvenile mussels that have spent the summer in various outdoor culture locations are collected and brought back to the mussel building to over-winter. Culture locations have been selected to provide the juvenile mussels a diverse, natural food base (river water) in a secure location (Dubuque’s Ice Harbor, in partnership with the National Mississippi River Museum and Aquarium, and Blackhawk Park, in partnership with the Corps of Engineers). After a summer of growth, mussels are collected, counted, cleaned, and measured. Individuals that have added sufficient growth over the summer are tagged and released at the end of the fall, others over-winter in rearing pans in the mussel building.  This summer, juvenile mussels were placed supsys (Suspended Upwelling SYStems) and newly transformed juveniles dropped off fish in cages in the Ice Harbor. Cages were pulled out of the water, cleaned and sorted by a wonderful group of volunteers, River Museum staff, Iowa DNR staff, and USFWS colleagues. Just over 2000 juvenile Higgins Eye mussels were recovered from the sandy substrate in the cages. Pictures of this event were featured on the River Museum’s social media pages, and on Genoa’s Facebook page. Supsys have been maintained all season by River Museum staff and student volunteers and will be end-of-season processed and returned to GNFH in October.
 

Juvenile Higgins Eye that spent the summer in the MARS trailer are now settled into their winter housing in the mussel building. Photo: Beth Glidewell/USFWS.

Many thousands of newly transformed juvenile mussels and older juveniles of 9 species spent the summer in the MARS (Mobile Aquatic Rearing System) trailer at Blackhawk Park. These juveniles are being counted, measured, and returned to the mussel building throughout the fall. A couple of very dedicated volunteers joined GNFH and other USFWS staff in the processing and counting of cages placed in Pond 14 at the hatchery. This was the 3rd year of an experiment evaluating polyculture methods and pond management. This year’s experiment did not yield any newly transformed juvenile mussels, though about 1000 older Fatmucket juveniles survived and grew to sufficient size in the pond that they can be tagged and released this fall. By: Beth Glidewell

USFWS staff and volunteers recovering mussel cages from Dubuque’s Ice Harbor at the National Mississippi River Museum and Aquarium’s dock. Photo: Erica Rasmussen/USFWS.

Volunteers helped count, sort, and record length measurements of the juvenile Fatmucket recovered from cages placed in Pond 14. Photo: Beth Glidewell/USFWS.

Teachers and students from Black River Falls listen to Fish Biologist, Nick Bloomfield explain about pond harvest.

October is one of the busiest months of the year at the Genoa National Fish Hatchery. October means pond harvesting time. This is the time to see what a summer worth of feeding and careful water monitoring has produced. It also offers excellent opportunities for outdoor education. Just ask Steve Teeples and his students from Black River Falls. Mr. Teeples class helped kickoff this year’s pond harvesting season starting with our smallmouth bass pond.  The students eagerly put on waders and jumped into the pond toassist by scooping up hundreds of smallmouth bass and transferred them to the USFWS hatchery truck. It was great to see the excitement on their faces as they assisted with the task and learned about the life cycle of the smallmouth bass. They also learned how smallmouth bass are a host fish used in the reproduction of freshwater mussels.

Students scooping up fish in net.

In total, 9,169 smallmouth bass were harvested from the pond. Some of the bass will be distributed to federal, tribal, and state agencies to be stocked in water bodies, used in the production of freshwater mussels or kept for future broodstock.
I may be a little biased, but I honestly believe that these hands-on outdoor opportunities are vital for students’ education. It allows students to use all of their senses to interact with the natural world while assisting the hatchery with a necessary task. It also exposes them directly to natural resource based career opportunities. If you have any interest in volunteering or bringing a class to the Genoa National Fish Hatchery, please feel free to contact me. By: Erica Rasmussen

The last cohort of mussels produced during the Summer 2021 season – a small cohort of Sheepnose mussels– have just completed development and are dropping off their golden shiner fish hosts in these first weeks of August. Sheepnose broodstock were collected in mid-July from the Chippewa River, and several hundred golden shiners were inoculated with the viable glochidia, or larvae, gathered from the collected females. Sheepnose are ‘short term brooders’ meaning the females don’t retain the mature glochidia for very long, so time is of the essence during propagation season. Water temperatures and river conditions in mid-summer dictate the spawning and then larval development timing, with female Sheepnose holding viable glochidia for a period as short as a couple of weeks. High water flows in the Chippewa prevented Sheepnose broodstock collection during the 2020 season, so we were pleased to find good river conditions for the collection and return of brooding females for this year.

A brooding plain pocketbook female buried in river sediment, prior to collection. Photo: Megan Bradley/USFWS.

This year’s newly transformed Sheepnose juveniles join cohorts of Black Sandshell, Plain Pocketbook, Hickory Nut, Lilliput, and two large cohorts of Higgin’s Eye juveniles in the MARS trailer, which were produced earlier in the season. These species, in addition to small cohorts of Rock pocketbook and Snuffbox which have been cultured in sediment trays at the mussel building, are all ‘long term brooders’ meaning females hold mature glochidia for longer periods of time, and can be collected sometimes months prior to fish host inoculation and juvenile production. As you can imagine, this makes production scheduling quite a bit easier!

A newly transformed Sheepnose juvenile, viewed under a dissection scope, this juvenile is about 1/3 of a millimeter long. Photo: Beth Glidewell/USFWS.

Staff from the La Crosse Fish Health Center visited the hatchery as part of a bi-annual fish health inspection. The Fish Health Center provides fish health inspection and diagnostic services for six national fish hatcheries and numerous tribal hatcheries throughout the region. In the spring staff sample hatchery production fish for possible pathogens or diseases. The results of these surveys ensure quality fish being stocked in the fall each year. In addition to hatchery production samples, Genoa provides a variety of fish from the Mississippi River for the fish health center as part of ongoing national wild fish health surveys. These sample collections and surveys allow fisheries managers to prevent and diagnose hatchery and wild populations of fish for pathogens or diseases. These results allow safe transport and stocking of healthy fish throughout many regions.
By: Orey Eckes

Fish health biologist, Eric Leis samples lake sturgeon. Photo Credit: Jadon Motquin/USFWS

Summer mussel propagation at the MARS trailer

The MARS (Mobile Aquatic Rearing System) mussel culture trailer is set up and running for the 2021 season at Blackhawk Park, a US Army Corps of Engineers facility just south of Genoa. This location allows us to securely park the trailer on the banks of Blackhawk Slough, and to pump river water directly up to the trailer, where it is filtered, UV zapped, and routed to 25 rectangular flow-through tanks. Each tank houses up to 250 sub-adult mussels, each about 1 inch long, or five thousand (or more!) newly transformed juvenile mussels that are about the size of a grain of sand.

Each year is different when dealing with water levels- after a couple of years of delayed trailer deployment due to high water and last year’s surprisingly ‘normal’ water levels (the only thing normal about 2020!), this year we’ve been dealing with low water situations. Low water helped simplify set-up (a big thank you to Jeff and Zach!), but reduced flow and connectivity to the main channel reduced water quality, especially dissolved oxygen in Blackhawk Slough, and reduces flow capacity from the pump. Just as we were considering starting contingency plans, much needed rains came and raised the water levels back to functional levels in mid-June.

This year’s MARS trailer group includes two sub-adult cohorts of Higgins eye, a group of Spectaclecase mussels propagated by the MN DNR, Fatmucket, and small cohorts of Sheepnose and Lilliput mussels. The newly transformed 2021 cohorts began in late June, and now include Pocketbook, Black Sandshell, Hickorynut, Lilliput, and two sub-groups of Higgins eye, including fifty thousand -and counting- juveniles produced from parents in the St Croix River. Watch for pictures of these juveniles on Genoa’s Facebook page, and an article later in the year reporting their growing season progress!

By: Beth Glidewell

Newly transformed Higgins Eye that will spend their first growing season in MARS tanks. Each juvenile is ~0.3 mm long (or about 1/80th of an inch) when they go into the tanks at the start of the season. Photo: Beth Glidewell