We’re delighted to share the findings from our 2026 seasonal fish surveys - and to thank the many Creekside volunteers who helped gather the data. Across six spring and summer sessions, volunteers and staff recorded a striking seasonal shift in the fish using the creek. April’s survey found no fish, but by September the team recorded 37 in a single session. In total, the surveys logged 90 fish across seven recorded groups, offering a fascinating snapshot of a dynamic urban intertidal habitat.

The season at a glance

The clearest pattern was the sharp rise in catches towards the end of the season. August and September accounted for 64 of the 90 fish recorded—just over 70% of the total. This increase coincided with the first brackish readings noted in the survey sheets: 3.5 ppt in August and 3 ppt in September, compared with zero in April and May. It is an interesting association, although six surveys are not enough to conclude that salinity caused the increase.

Species trends

Sea bass were the standout fish of the season. After a single 110 mm specimen was recorded in May, the surveys found eight in July, 23 in August and 30 in September. Altogether, sea bass accounted for 62 of the 90 fish - about 69% of the catch. Most measured between 40 and 120 mm, while September produced the largest sea bass of the series at 210 mm.

Eels were the second most frequently recorded group, with 20 individuals found across every survey from May onwards. They ranged in length from 150 mm to 600 mm. June’s catch consisted entirely of five European eels, while August produced the season’s largest individual: a 600 mm eel.

The smaller numbers of other species reveal a more varied picture of life in Deptford Creek. Three flounder were recorded across May and July. August brought a carp and a goby, while September added a minnow and two dace. These occasional finds broadened the season’s species mix beyond the dominant sea bass and eels - and show why repeated surveys are so valuable.

What the first look suggests

Late summer was busiest: catches climbed sharply in August and September.

Sea bass drove the increase: they made up more than two-thirds of all fish recorded.

Eels were a consistent presence: they appeared in five consecutive monthly surveys and spanned a wide range of sizes.

The creek’s conditions changed: recorded water temperature rose from 15°C in April to 24°C in July and August, while measurable salinity appeared in the final two surveys.

Consistent recording will improve future comparisons: creek temperature or salinity data was missing in June and July, and volunteer details were completed only in September.

Further opportunities for our volunteers

Creekside has recently launched Wild Tide, a Mayor of London-funded project that brings local people together to restore habitats, survey wildlife and help shape the future of Deptford Creek. Through the project, we are creating a Deptford Creek Wildlife Taskforce whose volunteers will take part in bird, fish, plant and water-quality surveys, alongside habitat creation and restoration, until August 2027. By joining the Taskforce, you can strengthen the project’s impact and help build a more resilient future for the creek. Follow the link above to visit the project webpage and register your interest.

Finally, thank you to everyone who brought their time, curiosity and care to Creekside Education Trust’s 2026 fish surveys. Every survey adds another piece to our understanding of how fish use Deptford Creek through the seasons - and supports our work to create a resilient, thriving environment for its wildlife and communities.