Fisheries Survey

SUMMARY OF RECOMMENDATIONS

1. Nutrient inputs
Nutrients are entering Ryerson Lake via tributaries, from runoff in the watershed, and being regenerated by anoxic sediments (internal loading). Problem areas and suggested solutions follow:

A. Septic tanks: they seep into the groundwater through permeable sand. They must be pumped often, at least once every 2 yr. Switching to sewers is the best alternative.

B. Sediments can generate nutrients near bottom in the deep basin during decomposition processes in winter and summer (internal loading). Reducing nutrient input from riparians, so less organic material accumulates on the bottom is one thing riparians can do along with reducing tributary inputs of nutrients (see C below). More expensive, but proven, solutions include: alum treatments and hypolimnetic aeration (aerating only the bottom nutrient rich water).

C. Tributary inputs. We documented large amounts of nitrates (7.88 mg/L) in the NW Sandbar tributary in spring. High concentrations of nitrates and phosphorus were also recorded in the other four tributaries.

Some of these nutrients are being taken up by wetland vegetation, shoreline plants, and macrophytes in the lake near the tributary mouths. However, these sources are a problem year round and probably substantial sources of eutrophication (nutrient enrichment) in Ryerson Lake. Obviously, since there are large agricultural lands in the watershed feeding these tributaries, they would appear to be the source of most of these nutrients. Hence, there should be an attempt to persuade farmers directly in the watershed to follow best management practices to reduce nutrient runoff from their fields.

There are Michigan State Extension agents that might be able to assist in this effort. In addition, attention should be directed to the mouths of these tributaries to maintain a dense macrophyte bed to absorb nutrients – exercise care in any herbicide treatments of these plants. Finally, consult the results of the ongoing study of the watershed being conducted by nearby lake associations.

D. Runoff, lawn fertilization, and other activities by residents contribute nutrients: Observe suggestions in Appendix 1 – greenbelts, no fertilization of lawns, ban pet wastes from lawns, no leaf burning at the lake, reduce impermeable surfaces, etc. Consider the no mow vow for spring to promote pollinators; reduce runoff from rain events.

E. Waterfowl, such as Canadian geese, need to be discouraged from visiting, nesting, or hanging around the lake eating lawns.

2. Northern Pike
We think northern pike are now not as abundant during 2021 as they were during 2014 and they appear to be growing at state averages.

We would support a return to normal catch limits for this species.

3. Largemouth Bass
We recommend catch and release for all largemouth bass >15 inches, unless fish are foul hooked and would die. They help control stunting in sunfish populations, despite that we think they may be responsible for the loss or diminution of six species of minnows.

4. Yellow perch
Yellow perch were not very abundant during 2014 or 2021, but there were quite a few young in the near shore zone so they still are reproducing at acceptable levels.

Many top predators fed on them, so not much can be done. If the northern pike population is reduced, perhaps we may see increases in survival of this species to larger sizes.

5. Walleye
Walleye have been stocked into Ryerson Lake. Amazingly many have survived, providing a small fishery.

We oppose further stocking, because they are not native, they are difficult to catch, they will not spawn, stocking may introduce diseases, and most importantly, they will be severely stressed during summer stratification.

6. Prevent Exotic Species from Entering Ryerson Lake
Prevent exotic species, besides Eurasion milfoil which has already been introduced, from entering the lake.

Consider banning bait from outside the lake to avoid the introduction of more exotic species, such as quagga mussels and VHS.

Fishers and skiers need to dry out boats and gear that come from other lakes that might be contaminated with exotic species, such as zebra mussels.