| Code | Description | Introduced | Final | Retainable | MHR | Catches | Removals |
|---|---|---|---|---|---|---|---|
| A | Accidental losses | Y | Y | Y | Y | Y | |
| B | Retained for use as bait | Y | Y | Y | Y | Y | |
| BD | Return of damaged fish (balanced) | 2026-10-01 | Y | Y | Y | Y | Y |
| E | Catch eaten on board | Y | Y | Y | Y | Y | |
| EOY | End of year landings | 2017-10-01 | Y | Y | Y | Y | Y |
| H | Losses from holding receptacles | Y | Y | Y | Y | Y | |
| HL | Losses from holding receptacles on land | 2018-07-01 | Y | Y | Y | Y | Y |
| HW | Losses from holding receptacles in the water | 2018-07-01 | Y | Y | Y | Y | Y |
| J | Observer or Fishery Officer authorised returns | 2013-10-01 | Y | Y | Y | Y | Y |
| L | Landings to an LFR | Y | Y | Y | Y | Y | |
| LFL | Fish landed after being held live on land | 2019-01-10 | Y | Y | Y | Y | Y |
| LP | Final landing of fish from holding receptacles at sea | 2018-07-01 | Y | Y | Y | Y | Y |
| LR | Final landing of retained fish | 2017-10-01 | Y | Y | Y | Y | Y |
| M | Sixth schedule returns (spiny dogfish) | 2004-10-01 | Y | Y | Y | Y | Y |
| O | Catch transported outside the EEZ | Y | Y | Y | Y | Y | |
| PF | Predated fish | 2018-07-01 | Y | Y | Y | Y | Y |
| QL | Landings to an LFR after storing in a holding receptacle on land | 2018-07-01 | Y | Y | Y | Y | Y |
| QWM | Landings to a disposal facility after storing in a holding receptacle on land | 2023-10-11 | Y | Y | Y | Y | Y |
| S | Catch taken by a Fishery Officer or observer | Y | Y | Y | Y | Y | |
| T | Transhipments | Y | Y | Y | Y | Y | |
| TL | Transhipments, reported as landed by the catching vessel | 2018-07-01 | Y | Y | Y | Y | Y |
| U | Used as bait | Y | Y | Y | Y | Y | |
| W | Wharf sales | Y | Y | Y | Y | Y | |
| WM | Landings to a disposal facility | 2023-10-11 | Y | Y | Y | Y | Y |
| Z | Returns to the sea (certain sharks, dead or near-dead) | 2014-10-01 | Y | Y | Y | Y | Y |
| BS | Biotoxin samples | 2019-11-26 | Y | Y | N | Y | Y |
| CS | Customary catch | 2017-10-01 | Y | Y | N | Y | Y |
| D | Non-QMS returns | Y | Y | N | Y | Y | |
| F | Landings as recreational entitlement | 2002-07-11 | Y | Y | N | Y | Y |
| I | Returns for safety of protected species | 2022-11-01 | Y | Y | N | Y | Y |
| UD | Return of damaged fish (unbalanced) | 2024-06-01 | Y | Y | N | Y | Y |
| V | Observer samples | 2017-10-01 | Y | Y | N | Y | Y |
| X | Permitted returns | 2006-10-01 | Y | Y | N | Y | N |
| C | Disposal to the Crown | Y | Y | Y | Y | ||
| FC | Return due to commercial take restriction | 2026-10-01 | Y | N | N | N | N |
| G | Returns above legal size | 2018-07-01 | Y | N | N | N | N |
| K | Lobster required returns (not sub-MLS) | 2018-07-01 | Y | N | N | N | N |
| Y | Sub-MLS returns | 2017-10-01 | Y | N | N | N | N |
| LF | Live fish held on land | 2019-01-10 | N | Y | N | N | N |
| N | Removals from holding receptacles at sea | 2018-07-01 | N | Y | N | N | N |
| P | Placed into a holding receptacle at sea | N | Y | N | N | N | |
| Q | Placed into a holding receptacle on land | N | Y | N | N | N | |
| R | Landings retained on board | N | Y | N | N | N | |
| TT | Transhipments, reported as landed by the receiving vessel | 2017-10-01 | N | Y | N | N | N |
4 Catches and removals
A key process in the build of the kahawai database is the allocation of catches to individual fishing events. Here, catches refers to the quantities of fish reported as either landings or disposals, and that are treated as trip-level data (in practice, some disposals are linked to individual events).
There are a number of nuances in the reporting regime that affect how catches are calculated in the kahawai database. These are described here, together with the rationale for the treatment adopted.
4.1 Conversion factors
Some fish are landed whole and intact (these are referred to as being in a “green” state), but some fish are processed at sea (for example, by removing the head and guts) with the result that the weight measured when the fish are landed is the weight of processed fish (the “processed weight”) rather than the original “greenweight”. In these cases, the greenweight is reported by multiplying the processed weight by a conversion factor. Conversion factors are regulated values, specified by processed state, or by species and processed state. (Vessel-specific conversion factors may also be defined for certain species and processed states where observers have carried out specific observations.)
Over time, and usually following at-sea monitoring by Fisheries New Zealand observers, conversion factors may be recalculated, or defined for new species-state combinations. Conceptually, a conversion factor may change because of subtle changes in way fish are processed while not departing sufficiently from the relevant processed state definition. However, we assume that most changes in conversion factors are the result of improved knowledge around the relationship between processed and green weights for particular species processed to certain states. As a result, the approach taken in the kahawai database is to re-scale the reported greenweights for landing and processing records to the greenweight that would have been reported had the current conversion factor been applied.
This step is applied before any grooming rules are applied, with the reported greenweight moved to a separate database field to ensure it remains available for use in later analyses.
4.2 Secondary processed states
Some fish are processed at sea into multiple parts, for example the main body of the fish and some by-products (e.g., heads, livers, etc.). In this case, the greenweight is estimated by applying the conversion factor to the largest part remaining after processing, referred to as the primary processed state. If the greenweight were also estimated from the secondary products, then the fish would be double-counted.
Some processed states may be the primary product from a fish in some cases, or a secondary product on other occasions: these circumstances are allowed for by defining different state codes for the product (i.e., identifying it either as the primary landed state, or a secondary product).
Greenweights should not be included in records of secondary products but, as a safeguard against double counting, all records of secondary product states are dropped from the landings data as part of the data grooming.
4.3 Non-final landings
The reporting regime requires that some fish are “landed” more than once; for example, if fish are stored before they are finally transferred to a Licensed Fish Receiver. To avoid double counting, only the final landings are included in the catches. Records of non-final landings are “dropped” (moved to a different table). The categorisation of destination codes as final or non-final is provided in Table 4.1.
4.4 Required returns
Fish in certain states cannot be legally retained and must be returned to the sea; for example, fish below the minimum legal size (MLS). Over time, the reporting regime has evolved to required these returns to be recorded as “disposals”; for example, snapper below the MLS caught in the SNA 1 Quota Management Area were reported using the SNX code from 1 March 2014. Subsequently, the requirement to report disposals of all fish below the MLS was introduced as part of the Electronic Reporting regime. Prior to these changes, the quantity of fish below the minimum legal size that was caught and returned was explicitly excluded from reporting (although the historical reporting obligations for other required returns were not as clearly defined).
To provide a temporally consistent definition of catches, we use this term to mean the catch of legally retainable fish. Disposal records for fish that are not legally retainable are dropped as part of the data grooming. The destination codes used for legally required returns are noted in Table 4.1.
4.5 Optional returns
Under certain, restricted circumstances, fishers are allowed to return fish to the sea that would have been legally retainable. Evolution of the reporting regime has seen the introduction of more detailed recording of such disposals; for example, the introduction of destination code X from 1 October 2006 that (in a general sense, at least) aimed to record the quantity of fish returned to the sea that was considered likely to survive.
Unlike required returns, fish that are optionally returned to the sea are not dropped during grooming. However, while such fish are considered to be part of the catches, they are not generally considered to be removals from the stock.
4.6 Cautions
Although the kahawai database build implements a consistent approach to defining catches, some cautions around the interpretations made are warranted. For example:
- the MLS for some fish species has changed over time; and
- some reporting changes have removed ambiguity around whether optional returns were to be reported: the extent to which these were reported prior to the reporting changes may be fishery-specific.
Catches include declared accidental losses of fish but do not include fish that escape capture; for example, by escaping through the mesh of a trawl.
In general, data users must consider the history of regulations and practices that have applied over time in any given fishery.