DOI: 10.20393/26cc442e-8b40-418f-add2-24111bb1ef8f
title: Nephrops (Nephrops norvegicus) Underwater TV Surveys, Marine Institute Ireland, 2002 - Present

description: Nephrops norvegicus is a lobster also known as the Norway lobster, Dublin Bay prawn, langoustine or scampi. Nephrops are one of the most valuable demersal fisheries in Europe. They are common around the Irish coast, occurring in geographically distinct sandy or muddy areas where the sediment is suitable for construction of their burrow dwellings.

The Marine Institute conducts Underwater TV (UWTV) surveys annually of commercially important Norway lobster (Nephrops norvegicus) grounds following ICES Survey protocols( https://doi.org/10.17895/ices.pub.8014) . Nephrops grounds are managed and assessed across Europe as individual stocks as Functional Units (FUs). This survey dataset provides quality assured estimates of Nephrops burrow densities over the known spatial and bathymetric distribution grounds within FUs: 16,17,19, 22 and 20-21. This dataset covers the period of 2002 and is ongoing. 

Functional Units:
FU 16: Porcupine Bank Nephrops grounds.
Survey series commenced in 2012.
100% of the survey grid was covered in all years except in 2012, where sixty-nine percent of the grid was covered (47 stations), and in 2015, no survey data are available due to research vessel breakdown. Survey design is a randomised isometric grid of UWTV stations at six nautical mile spacing. Water depth ranges from 290 to 585 metres.

FU 17: Aran, Galway Bay and Slyne Head Nephrops grounds.
Survey series commenced in 2002. 
Survey 100% of the survey grid was covered in all years except in 2003 and 2008, no survey data for Slyne Head, and in 2022, no survey data for Aran and Slyne Head grounds, all due to logistical problems. Survey design is a randomised isometric grid of UWTV stations at 4.5 nautical mile spacing on the Aran grounds and random stratified for Galway Bay and Slyne Head grounds. Water depth ranges from 21 to 125 metres.

FU19: 
In 2006, 6 stations only were completed as an exploratory survey. The 2006 is provided in this dataset. There was no survey was carried out in years 2007 to 2010 due to time constraints. Survey design is a random stratified for the discrete Nephropsgrounds in this FU. Water depth ranges from 27 to 149 metres.

FU20-21: Labadie, Jones and Cockburn Banks Nephrops grounds. 
Survey series commenced in 2013.
One hundred percent of the survey grid was covered in all years except in 2013, where 56% of the grid was covered (55 stations) and 2024 where 90 percent of the grid was covered (84 stations), all due to logistical problems. Survey design is a randomised isometric grid of UWTV stations at 6 nautical mile spacing. Water depth ranges from 73 to 149 metres.

FU22:The “Smalls” Nephrops grounds.
Survey series commenced in 2006. 
Survey 100% of the survey grid was covered in all years except in 2015, where 83 percent of the grid was covered (33 stations). Survey design is a randomised isometric grid of UWTV stations at 4.5 nautical mile spacing. Water depth ranges from 74 to 145 metres.

Dataset fields are Nephrops Functional Unit Number; Survey Code; Year; UWTV station number; Date-Start of UWTV track; Time_Start of UWTV track; Date-End of UWTV track; Time_End of UWTV track; Decimalised longitude and latitude midpoint of the UWTV station track; Adjusted density (Nephrops burrows/m²) ;Length in metres of the UWTV station track; Field of View of camera system in metres; Total Nephrops burrow count; Nephrops Fishing Ground Name; Source of positional data to calculate UWTV station track (USBL sled GPS, SHIP GPS, Layback, estimated GPS); Camera system used (SD = standard analogue system, HD = high definition system); Data Status (Final for analysis); Research Vessel Name; Correction Factor (Density / Correction Factor = Adjusted Density) and Water Depth (metres).