INTERIM FISH REPORT

OCTOBER 18, 2004

THOUGHTS ON SHAD AND STRIPER MOVEMENTS

We have seen an interesting cycle of movement with shad and stripers. Most of the year shad have held over the deep water of the main channel from Wahweap to Good Hope. With full moon during the last week of September shad moved out of the channel and into the coves during the day. Boils ceased in open water as stripers seemed to lose contact with shad.

Then some striper feeding activity was seen in coves off the main channel but in close proximity. Both shad and stripers were moving and could not be counted on to reappear in the exact same location from day to day. Shad in high abundance in the back of long canyons far from the channel were unmolested by stripers.

Shad trawl sampling from Trachyte to Wahweap from October 12-16 found shad in peak abundance at the Colorado River inflow near Trachyte (2000/tow). Bullfrog, San Juan, Wahweap all had similar shad abundance at a high level (20-50/tow) for this late in the year. These shad were caught in open water so it is obvious that shad were moving out of cover into the channel after dark.

Now in Mid October stripers have moved into canyons holding resident shad schools.

The progression is logical in retrospect. Small shad in the main channel are easy targets. No need to chase adults when slow swimming young are easy prey. As young shad finally grew larger and left the channel to avoid the daily attacks, stripers lost contact and had to look on shore instead of looking straight up for a meal. Lack of large open water shad schools caused stripers schools to fragment as feeding in coves did not take a large striper school for feeding success. Small numbers of shad in coves became less desirable for stripers who want more prey. Now probes into canyons far way from the channel are beginning and striper schools are reforming to work over the larger shad schools in canyons.

Looks to me like the stripers are just reloading for a strong feeding spree in November. Water temperature is still favorable for shad to stay shallow for a few more weeks. The battleground now becomes the long canyons where water depth is 40-60 feet. This is the winter holding area for both species. Neither has gone deep so boils will be seen in coves near main canyon channels for the short term.

This will be the time to look between Good Hope and Trachyte (highest shad density on the lake) for intense striper feeding activity.