Chub Mackerel

(Scomber japonicus)

Pacific chub mackerel, Chub, Chub mackerel

1. What is it?

Chub Mackerel ( Scomber japonicus) are small, pelagic fish that form large schools based on size and will occasionally form schools with sardines. Chub Mackerel have a long life span indicating a moderate vulnerability to fishing pressures. The overall stock status for FAO 61 is uncertain. Stock status for FAO 71 is unknown due to a lack of information on catches.

2. How was it caught or farmed?

Japan - Pole and line

Chub mackerel are caught in the pole and line fishery. In this type of fishing, rigid poles (2-3 meters) are attached to a feathered jig containing a barbless hook attached by a short piece of line. There is limited information available on catches but due to selective nature of the fishing method catches of other species are unlikely. This fishing method has no negative impact on the benthic habitat or surrounding environment.

Japan - Stationary uncovered pound nets

Chub mackerel are caught using stationary uncovered pound nets. Stationary uncovered pound nets consist usually of net walls anchored or fixed on stakes, reaching from the bottom to the surface. The nets are open at the surface and include various types of fish herding and retaining devices. They are mostly divided into chambers closed at the bottom by netting. This gear poses a serious threat to marine mammals, especially to the local sub-population of common minke whale. For stationary pound nets, bycatch is unlikely, as any unwanted fish can be released. The fishery is unlikely to cause negative ecosystem changes.

Japan - Purse seine

Chub mackerel are targeted or caught as bycatch within the purse seine fishery for jack mackerel. Purse-seine nets are set around a school of fish in the surface to mid-water. Once the school is surrounded the bottom of the net is closed by a footrope. There is little information available on impact to endangered, threatened or vulnerable species as well as levels of bycatch. In addition, there is very little information available regarding the proportion or survival of discarded species. The fishery is not destructive to the habitat.

FAO 61 - Midwater trawl

Chub Mackerel are targeted or caught as bycatch using mid-water trawls. Midwater trawl nets are very large with a minimum mesh size of 75mm when stretched to maximum size. Trawling takes place in the zone between the seabed and surface of the sea and the net is dragged through the water without touching the seabed. There is little information available on impact to endangered, threatened or vulnerable species as well as levels of bycatch. Catches of juvenile horse mackerel are also unknown but thought to be decreasing. In addition there is very little information available regarding the proportion or survival of discarded species. There is no known damage to benthic habitats.

FAO 71 –Purse seine

Chub mackerel are targeted or caught as bycatch within the purse seine fishery for jack mackerel. Purse-seine nets are set around a school of fish in the surface to mid-water. Once the school is surrounded the bottom of the net is closed by a footrope. Impact on Endangered, Threatened and Protected (ETP) species is possible as Fish Aggregating Devices are widely used in the region. Current levels of bycatch and discarding are unknown. There is also no known damage to benthic habitat.

3. Where is it from?

Japan - Pole and line, Stationary uncovered pound nets and Purse seine

Chub Mackerel is fished around the Japan EEZ FAO 61 and imported into South Africa. Chub mackerel in Japan is managed as two separate stocks: the Pacific stock and the Tsushima Current stock. The overall management is partly effective. Although there is no specific management in place for chub mackerel, the fishery is managed through a number of regulatory measures including a Total Allowable Catch (TAC) limit, Total Allowable Effort (TAE), specific mesh sizes, minimum landing sizes and seasonal closures. An Ecosystem based management is currently at the state of implementation.

FAO 61 - Midwater trawl

Chub Mackerel is fished in FAO 61 by Japan, Russia, China and Korea and imported into South Africa. Management measures are indicated for fisheries in Japan and Russia. Chub mackerel are managed through a Total Allowable Catch (TAC) limit within the Japanese Exclusive Economic Zone (EEZ) and a multilateral management plan for the waters outside the EEZs is currently being developed. However the effectiveness of the management is currently unknown due to the lack of specific management.

FA0 71 – Purse seine

Chub Mackerel is fished in FAO 71 and imported into South Africa. No management measures are reported and given the level of uncertainty regarding the stock status; the fishery is essentially unmanaged. No management measures are in place for this fishery.