Logbooks are records of catch and effort registered at the time of the catch operation. The records can be in books or on electronic media. Data transmission to authorities can be at the time of landings or immediately after the fishing operation has been concluded and catches recorded. Logbooks are widely used as a method of collecting statistical information on commercial activities.

With the ever-growing amount of control being exercised in many fisheries, the provision of statistical information has become increasingly used or contemplated as a mandatory requirement for the granting of licenses or permits to fish. Even where no licensing system is in operation, but where monitoring of fishing activities forms an essential aspect of control, the need to maintain precise records of fishing operations in the form of logbooks is recognized and is frequently a mandatory requirement.

Logbooks record data in live weight and where these data are of sufficient quality dependent on the available weighing technology on board these data can replace the use of conversion factors.

The requirement for the use of logbooks is usually dependent on the size of the vessel and the fishery sector. For example, the European Union requires that all commercial fishing vessels over 10 meters in length should use logbooks, except when absent from port for less than 24 hours.

Logbooks may be considered as having two main functions:

1. Surveillance-orientated objectives, as a tool in the enforcement of fishing regulations and to ensure compliance with resource management controls
2. Data-orientated objectives, as a method of collecting primary fishery statistics and as a principal source of information on fishing inputs and outputs.

Logbooks have the important role as vehicles for data collection and two distinct major groups of users are:

1. Biologist-economist (fishing activity data, catch and effort data)
2. Control and enforcement authorities (especially under licensed fisheries schemes).

In most situations for the compilation of fisheries data, logbooks should not be considered in isolation, but as an essential component of an integrated system which includes other documentation, such as landings declarations and sales notes. The quantities of fish recorded in logbooks are weighed at-sea in often difficult working conditions on fishing vessels. As a result, the first opportunity to accurately record the quantity of fish is usually at the time of landing. The value of the logbooks from the point of view of the quantity of fish caught is in situations where on a single trip a vessel fishes in two or more fishing areas or uses two or more types of fishing gear. In such circumstances the quantities recorded in the logbooks may be used to allocate the quantities landed between the different fishing areas and/or methods. The other essential statistical information obtained from logbooks is the fishing effort responsible for the catches.

The recording of data on a fishing operation on a per gear deployment (or haul-by-haul) basis may not be essential and practicable. In such cases day-to-day records of fishing activity, or records from a fishing trip may be sufficient. However, separate records should be kept for each change of fishing gear or method and for each change of fishing area.

The most representative position of the gear deployment and/or retrieval should be recorded, indicating latitude and longitude (refer geographic coordinates). It should be mandatory to record the retained catch by species while recording of discarded catch separately is strongly recommended (refer catch and landings).

Recommended entries at the head of a logbook page, irrespective of the tailoring to different circumstances:

1. Vessel name
2. Vessel flag (nationality)
3. Vessel registration number and/or IMO number (if available)
4. Radio call sign
5. Trip number (where appropriate)
6. Master's name
7. Name of partner vessels (where applicable)
8. Flag (nationality) of partner vessel
9. Registration number of partner vessel
10. Type of gear (a separate entry for each gear)
11. Gear specifications (e.g. mesh size)
12. Port of landing (or name, nationality and registration number of the vessel to which catch is transhipped)
13. Quantity of fish landed or transhipped
14. Date of landing or transhipment.

Days when there is no fishing activity conducted, for example due to bad weather, loading, unloading, repairs, steaming, etc., should also be recorded in the logbook.

Vessel transmitted information

Vessel transmitted information (VTI) includes the reporting of catch, effort and entry and exit notifications, and may be supplemented by data from a vessel monitoring system (VMS) or an automatic identification system (AIS) which are submitted by a fishing vessel at timed intervals. VMS and AIS report the movement of a vessel at timed intervals through the automatic transmitting of the vessel's position via satellite, telephone or radio to a land-based station. The frequency of this transmission may vary between every 6 hours to every few minutes. VTI and especially VMS and AIS have been mainly used for control and enforcement purposes; however, recently VTI is proving useful in transmitting catch and effort data and in modelling the impact of fishing effort.

Combining information from logbooks and VTI, possibly adjusted by landings data, can provide detailed maps of fishing activities (e.g. Taconet, M., Kroodsma, D., & Fernandes, J.A. 2019). Technologies are now available that allow the logbook data to be transmitted to a shore station shortly after each fishing operation has been completed using e-logbooks.

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Eurostat. 1998. The collection and compilation of fish catch and landing statistics in member countries of the European Economic Area. European Commission. 112 pp. (also available at https://ec.europa.eu/eurostat/cache/metadata/Annexes/fish_ld_esms_an1.pdf).

FAO. 1998. Fishing operations 1. Vessel monitoring systems. FAO Technical Guidelines for Responsible Fisheries No. 1, Suppl. 1. Rome, FAO. 58 pp. (also available at http://www.fao.org/3/a-w9633e.pdf).

FAO. 1999. Guidelines for the routine collection of capture fishery data. Prepared at the FAO/DANIDA Expert Consultation. Bangkok, Thailand. 18-30 May 1998. FAO Fisheries Technical Paper No. 382. Rome, FAO. 113 pp. (also available at http://www.fao.org/3/a-x2465e.pdf).

Pope, J.A. 1986. Guidelines for the establishment of logbook and related systems. FAO Fisheries Circular No. 793. Rome, FAO. 26 pp. (also available at https://www.nafo.int/portals/0/pdfs/sc/1987/scs-87-016.pdf)

Rana, K.J. 1997. Guidelines on the collection of structural aquaculture statistics. Supplement to the Programme for the World Census of Agriculture 2000. FAO Statistical Development Series No. 5b. Rome, FAO. 56 pp. (also available at http://www.fao.org/3/w7208e/w7208e.pdf).

Taconet, M., Kroodsma, D., & Fernandes, J.A. 2019. Global Atlas of AIS-based fishing activity - Challenges and opportunities. Rome, FAO. (also available at http://www.fao.org/3/ca7012en/ca7012en.pdf).