Elkhorn Slough Estuarine Research Reserve long-term crab monitoring database

The purpose of the long term crab monitoring program at Elkhorn Slough Reserve, 1994-2024 was three-fold. First, we wanted to assess the trajectories of the native crab populations, primarily the Oregon mud crab, Hemigrapsus oregonensis, the Lined shore crab, Pachygrapsus crassipes, and various cangrid crab species (mostly Cancer antennarius and Cancer productus). Secondly, we wanted to assess the population trajectory of the newly invading (at the time) European green crab, Carcinus maenas. Last, we wanted to optimize the probability of early detection of any new invasive crab species at Elkhorn Slough. Secondarily, we recorded any fish species, that went into the traps as by-catch. We used regular minnow traps, minnow traps with an enlarged opening in one end, and Fukui fish traps. All traps were baited (usually with anchovies), deployed at zero tidal height (relative to mean low water) and soaked for 24 hours. Upon retrieval, individuals were identified to species..., , # Elkhorn Slough Estuarine Research Reserve long-term crab monitoring database

Dataset DOI: [10.5061/dryad.0p2ngf2cg](10.5061/dryad.0p2ngf2cg)

## Description of the data and file structure

This dataset was for monitoring of native and non-native crabs at Elkhorn Slough, 1994-2003.

Consistent trapping methods were used (minnow traps, and collapsible Fukui fish traps. Sites varied over the years, but the most consistently trapped sites were Kirby Park and South Marsh, surveyed annually in fall (October or November).

Contact Elkhorn Slough Reserve's Research coordinator [[e-mail]](mailto:[e-mail]) for further information.

### Files and variables

#### File: elkhorn\_crab\_data.csv

**Description:** 

Important note:
In order to calculate crabs per trap, one needs to know how many traps were set on a given day. This information is found in the file: trap_days_elkhorn_crabs_csv that contains the following variables:

Date (sampling date), Month (samplin...,