Horseshoe Crab Spawning Survey

# Horseshoe Crab Spawning Survey

Survey data from 1999-2018 which denotes peak spawning occurrences by day and lunar period, proportion of spawning in May (coinciding with shorebird stopovers), average water temperature, index values for female and male crabs per square meter by beach and baywide, the annual sex ratio, and index of abundance per beach.

## Columns

Name | Socrata field name | Column name in `sgr mount` | Data type | Description |
---|---|---|---|---|

Baywide Male SD | baywide_male_sd | baywide_male_sd | Number | Standard Deviation - Statistical variation of Index of Spawning Activity (ISA) values for males |

Year | year | year | Number | Year of survey |

NJ % Female Spawning in May | nj_female_spawning_in_may | nj_female_spawning_in_may | Number | Proportion of females recorded during May of a given survey year on New Jersey Beaches |

Avg. Daily Water Temp. in May (°C) | avg_daily_water_temp_in_may_c | avg_daily_water_temp_in_may_c | Number | Average of daily water temperatures recorded at the National Ocean Service station at Lewes, DE (Station Identification Number 8557380) during the month of May in °Celsius |

Baywide Spawning Activity Lunar Period 1 | baywide_spawning_activity_lunar_period_1 | baywide_spawning_activity_lunar_period_1 | Number | The mean of the total number of female crabs per total area available for the spawning survey on all surveyed beaches. The first moon phase (new or full) in May around which surveying begins - 2 days before, day of, 2 days after. |

Baywide Spawning ActivityLunar Period 2 | baywide_spawning_activitylunar_period_2 | baywide_spawning_activitylunar_period_2 | Number | The mean of the total number of female crabs per total area available for the spawning survey on all surveyed beaches. The second moon phase (new or full) in May around which surveying occurs - 2 days before, day of, 2 days after. |

Baywide Spawning ActivityLunar Period 3 | baywide_spawning_activitylunar_period_3 | baywide_spawning_activitylunar_period_3 | Number | The mean of the total number of female crabs per total area available for the spawning survey on all surveyed beaches. The first moon phase (new or full) in June around which surveying occurs - 2 days before, day of, 2 days after. |

Baywide Spawning ActivityLunar Period 4 | baywide_spawning_activitylunar_period_4 | baywide_spawning_activitylunar_period_4 | Number | The mean of the total number of female crabs per total area available for the spawning survey on all surveyed beaches. The second moon phase (new or full) in June around which surveying occurs - 2 days before, day of, 2 days after (typically the last period of surveying). |

Total Beaches Surveyed | total_beaches_surveyed | total_beaches_surveyed | Number | Number of beaches on which the standardized form of the spawning survey was conducted baywide |

Baywide Male Spawning Activity | baywide_male_spawning_activity | baywide_male_spawning_activity | Number | The mean of the total number of male crabs per total area available for the spawning survey on all surveyed beaches. |

Baywide Male 90% CI Lower Limit | baywide_male_90_ci_lower_limit | baywide_male_90_ci_lower_limit | Number | 90% Confidence Interval - Lower limit of values where there exists a 90% probability of male horseshoe crab spawning activity |

Baywide Male 90% CI Upper Limit | baywide_male_90_ci_upper_limit | baywide_male_90_ci_upper_limit | Number | 90% Confidence Interval - Upper limit of values where there exists a 90% probability of male horseshoe crab spawning activity |

Number of Males per Female | numbermalesperfemale | numbermalesperfemale | Number | The number of males observed in a given spawning season per female observed during that same season. |

Baywide Male CV | baywide_male_cv | baywide_male_cv | Number | Coefficient of variation - Unitless description of the amount of variation relative to the mean Index of Spawning Activity (ISA), expressed as a percentage for males |

Baywide Female Spawning Activity | baywide_female_spawning_activity | baywide_female_spawning_activity | Number | Index of female horseshoe crab spawning activity - mean number of female crabs per square meter per night for Delaware and New Jersey beaches |

Baywide Female 90% CI Lower Limit | baywide_female_90_ci_lower_limit | baywide_female_90_ci_lower_limit | Number | 90% Confidence Interval - Lower limit of values where there exists a 90% probability of female horseshoe crab spawning activity |

Baywide Female 90% CI Upper Limit | baywide_female_90_ci_upper_limit | baywide_female_90_ci_upper_limit | Number | 90% Confidence Interval - Upper limit of values where there exists a 90% probability of female horseshoe crab spawning activity |

Baywide Female CV | baywide_female_cv | baywide_female_cv | Number | Coefficient of variation - Unitless description of the amount of variation relative to the mean Index of Spawning Activity (ISA), expressed as a percentage for females |

DE Male Spawning Activity | de_male_spawning_activity | de_male_spawning_activity | Number | The mean of the total number of male crabs per total area available for the spawning survey on all DE surveyed beaches |

DE Male 90% CI Upper Limit | de_male_90_ci_upper_limit | de_male_90_ci_upper_limit | Number | 90% Confidence Interval - Upper limit of values where there exists a 90% probability of female horseshoe crab spawning activity in Delaware |

DE Female 90% CI Lower Limit | de_female_90_ci_lower_limit | de_female_90_ci_lower_limit | Number | 90% Confidence Interval - Lower limit of values where there exists a 90% probability of female horseshoe crab spawning activity in Delaware |

NJ Male Spawning Activity | nj_male_spawning_activity | nj_male_spawning_activity | Number | The mean of the total number of male crabs per total area available for the spawning survey on all NJ surveyed beaches |

NJ Female 90% CI Lower Limit | nj_female_90_ci_lower_limit | nj_female_90_ci_lower_limit | Number | 90% Confidence Interval - Lower limit of values where there exists a 90% probability of female horseshoe crab spawning activity in New Jersey |

NJ Female 90% CI Upper Limit | nj_female_90_ci_upper_limit | nj_female_90_ci_upper_limit | Number | 90% Confidence Interval - Upper limit of values where there exists a 90% probability of female horseshoe crab spawning activity in New Jersey |

NJ Female Spawning Activity | nj_female_spawning_activity | nj_female_spawning_activity | Number | The mean of the total number of female crabs per total area available for the spawning survey on all NJ surveyed beaches |

DE % Female Spawning in May | de_female_spawning_in_may | de_female_spawning_in_may | Number | Proportion of females recorded during May of a given survey year on Delaware beaches |

DE Female Spawning Activity | de_female_spawning_activity | de_female_spawning_activity | Number | The mean of the total number of female crabs per total area available for the spawning survey on all DE surveyed beaches |

NJ Beaches Surveyed | nj_beaches_surveyed | nj_beaches_surveyed | Number | Number of beaches on which the standardized form of the spawning survey was conducted in New Jersey |

DE Male 90% CI Lower Limit | de_male_90_ci_lower_limit | de_male_90_ci_lower_limit | Number | 90% Confidence Interval - Lower limit of values where there exists a 90% probability of male horseshoe crab spawning activity in Delaware |

NJ Male 90% CI Lower Limit | nj_male_90_ci_lower_limit | nj_male_90_ci_lower_limit | Number | 90% Confidence Interval - Lower limit of values where there exists a 90% probability of male horseshoe crab spawning activity in New Jersey |

NJ Male 90% CI Upper Limit | nj_male_90_ci_upper_limit | nj_male_90_ci_upper_limit | Number | 90% Confidence Interval - Upper limit of values where there exists a 90% probability of male horseshoe crab spawning activity in New Jersey |

DE Female 90% CI Upper Limit | de_female_90_ci_upper_limit | de_female_90_ci_upper_limit | Number | 90% Confidence Interval - Upper limit of values where there exists a 90% probability of female horseshoe crab spawning activity in Delaware |

DE Beaches Surveyed | de_beaches_surveyed | de_beaches_surveyed | Number | Number of beaches on which the standardized form of the spawning survey was conducted in Delaware |

Baywide Female SD | baywide_female_sd | baywide_female_sd | Number | Standard Deviation - Statistical variation of Index of Spawning Activity (ISA) values for females |