Male smallmouth nested closer than a random draw on one closed lake

STEP 1 · Skew alone

A right tail can fake loyalty

Repeat breeders were males identified by tag as nesting in two consecutive years. Eight year pairs held 79 to 159 of them, and every pair showed a strong right skew in the distance from one nest to the next. Means ran about 560 to 850 feet (172 to 260 m) because the far males pull the average up. The longest move in a year pair fell between about 3,070 and 3,580 feet (937 to 1,090 m).

The authors illustrate the trap with a straight beach or a straight river shore. If breeders there pick a spot at random in two years, the gaps still bunch short and leave a long right tail.

STEP 2 · Lake-wide draw

Random males landed on this year's real nests

Crews snorkeled and watched from boats every day from mid-May through June and into early July if nests were still active. They netted guarding males and gave each untagged male a numbered anchor tag. Females spawned in 170 to 329 nests a year. Crews caught the guarding male on 89 to 98 percent of them and caught 152 to 284 unique males in a season.

The random model placed repeat breeders and males that were untagged when captured onto nests that received eggs the next year. Each year pair was redrawn 1,500 times. Because every male landed on a real nest from that second year, the draw kept males on bottom that held eggs and kept the spacing neighbors already used. Nothing else was imposed. The draw had no movement cap because the farthest nests on this lake are about 0.75 mile apart (1,200 m).

The main text says that added models with earlier nesting by larger males and with habitat preferences reached the same faithfulness conclusion.

Our read is that a gap against this draw belongs to a lake with about 2.5 miles (4 km) of shoreline. Read that gap as a comparison on this lake. Do not reuse it as a search radius on a larger or smaller water.

STEP 3 · Hundreds closer

Group means sat over 1,000 feet nearer than the draw

None of the 1,500 draws matched the observed distances in any year pair. Mean, median, skew and kurtosis also fell outside the simulated sets each year. Simulated means ran about 1,050 to 1,350 feet longer than observed means (320 to 412 m). The gap for medians was larger and averaged about 1,950 feet (594 m). As a group the real males nested closer than the random placements in every year pair. The authors conclude that at least some males were site faithful and that many may show some level of fidelity.

In three year pairs the draw could not be separated from the real spread of distances. Failing to separate those spreads is not proof the spreads matched. The center of the real distances still differed in every pair.

STEP 4 · Same marker

Exact reuse was uncommon but far above the draw

From 6 to 18 percent of repeat breeders guarded the exact same nest the next year. The yearly shares averaged 12 percent, about 1 in 8. The average share assigned back to last year's nest under the draw ran from about 0.03 to 0.16 percent. Observed shares sat outside every simulated set.

GPS fixes for nests within 1 m of the same permanent marker in consecutive years scattered by an average of about 12 feet (3.54 m) across 911 pairs. That figure is measurement scatter. Nearest nests averaged about 39 feet apart (12.0 m). A median move of about 150 to 390 feet is roughly 4 to 10 times that average gap. Our read is that the common return on this lake is to a stretch of shore. About 1 in 8 returning males used the same nest, so expect to search a neighborhood rather than one rock.

Up to 14 percent of captured males in a year spawned in two nests or occasionally three. The average share was 6 percent. For those fish the measured distance runs from the last nest of the first year to the first nest of the next.

STEP 5 · Where to look

Old neighborhoods first on water you can fish

Check the current rules for that water before you fish guarding males. The count below is for water you can legally fish and leaves the study lake out of the plan.

Our proposed observation is a paired count. Once males are up shallow, give equal time to last year's bed stretches and to a comparison stretch of similar bottom that held no beds. Count spots with eggs or hatched larvae and a male present. Repeat the count on more than one day while the spawn is still on.

More active nests on the old stretches than on the comparison stretch would show that those neighborhoods still hold beds this season on that water. That result would support starting there. Similar counts would mean the shortcut failed there. The count shows where beds are this year. It cannot show that the same males returned. Nests can cluster on suitable bottom. A stretch with no beds last year may be poorer ground. It cannot recover the modeled distance gap or tell you anything about bites.

The authors note that water level swings, wash-in and nearshore disturbance probably change what makes a good nest spot from year to year. That statement was not a test on Pallette Lake. Our rule is that after a change like that, a thin count on the old stretches is a reason to follow the comparison stretch.

Rivers and lakes that smallmouth can leave sit outside this paper. In four of the eight year pairs some repeat breeder went farther than about 3,280 feet (1,000 m), described as roughly 3,280 to 3,770 feet of shoreline (1,000 to 1,150 m). Why these males are site faithful is still open.