Land-based aquaculture

Land-based aquaculture is a general term for a form of aquaculture in which fish and shellfish are raised in facilities built on land. There are also other forms of aquaculture in coastal areas and offshore. Land-based aquaculture is the form of aquaculture closest to human habitation, and has the advantage of being easily managed by humans.

Increase in entrants and legal arrangements

Marine aquaculture requires a fishing license, but land-based aquaculture does not require a fishing license, making it easier for new entrants to enter the industry, and the scale of the industry has been expanding in recent years. In light of this, the Fisheries Agency has designated land-based aquaculture as a notified aquaculture industry under the "Law Concerning the Promotion of Inland Water Fisheries," which came into effect on April 5, 4.^*1This notification system will enable the government to grasp the actual situation of land-based aquaculture and promote its position as an industry.

Illustration: Provided by Associate Professor Masato Endo, Department of Marine Biological Resources, Tokyo University of Marine Science and Technology

Water Use and Its Benefits

Land-based aquaculture can be divided into three types based on how water is used. There are "flow-through aquaculture," in which irrigation water is taken in and used directly or after filtering, and is used only once; "semi-recirculating aquaculture," in which the amount of water taken in is reduced and filtration equipment is installed to stabilize the environment; and "closed-recirculating aquaculture," in which filtration equipment is used to minimize water replacement and maintain water quality.^*2(See figure below).

Regarding water, in addition to filtering surface water, underground seawater is increasingly being used to maintain its purity and stabilize its temperature and quality. In closed circulation aquaculture, it is possible to use artificial water for rearing, in which tap water is added with the salts necessary for the fish and shellfish raised there, which prevents infection with pathogenic microorganisms and viruses. Wild-caught fish are often infested with Anisakis, which is harmful to humans, and if they are eaten raw without being refrigerated or thawed, the Anisakis will cause severe abdominal pain if it enters the human body. In land-based aquaculture, the feed is controlled, which prevents Anisakis from infesting farmed fish, and in recent years, there has been an increase in land-based aquaculture of chub mackerel for consumption raw.^*3.

In addition, normally, tiger pufferfish become poisonous when they eat toxic food, but in land-based aquaculture, they are not fed toxic food, so there is an advantage that they do not become poisonous.^*4.

Environmental Control Technology

Land-based aquaculture has the advantage that the light environment can be freely controlled by using facilities, and by optimizing light and feeding, it is possible to promote growth and control reproduction. It has been found that raising flounder and plaice under green light promotes their growth, and that blue light can promote the growth of groupers, and some of these methods have been put to practical use.^*5Furthermore, in the case of tilapia, a species native to Africa that is being farmed worldwide, it has been found that while they are normally raised with a shorter photoperiod of 12 hours of light and 12 hours of darkness, alternating between three hours of light and three hours of darkness promotes their growth. With regard to reproduction control, it has been found that for many fish species, the photoperiod during the spawning season promotes the formation of eggs and sperm, and it has also been found that in the case of the aforementioned tilapia, egg and sperm formation is suppressed when the fish are raised in an environment with a six-hour light and dark cycle.^*6.

Business profitability and reduced environmental impact

However, the initial costs for facility construction and water intake equipment, as well as the high energy costs required to operate the aquaculture equipment at the facility, are cited as disadvantages. In this regard, it is necessary to reduce costs by utilizing existing disused buildings and water intake equipment, utilizing waste and surplus energy, and increasing productivity through the above-mentioned environmental control. In addition, sales strategies such as branding that take into account business profitability are also key to the success of land-based aquaculture. Regarding the discharge of water pollutants, a treatment method that minimizes discharge into the natural environment as much as possible under proper management is required. In particular, aquaponics is considered to be an effective method of utilizing these water pollutants, in which precipitated substances such as feces are collected and spread on fields, or dissolved substances in liquid form are used as fertilizer for vegetables and seaweed.^*7.

*1 Notification system for land-based aquaculture to begin in April 5 (Fisheries Agency, Aquaculture Division, 4)
*2 Current status and issues of land-based aquaculture: salmon land-based aquaculture as a demonstration example (Imai Satoshi, Aquaculture Production Group, Resources and Fisheries Department, Seto Inland Sea Fisheries Research Institute, Fisheries Research and Education Agency, 2018)
*3 Recreating the sea on land!! We have succeeded in cultivating "land-born and land-raised" [fully land-farmed mackerel]! ~ You can eat safe mackerel without Anisakis ~ Available from Wednesday, March 3th "Mackerel Day" (Fish Biotech Co., Ltd. press release, March 8, 2023)
*4 Where does the poison come from? "Pufferfish do not produce pufferfish poison" (Seizando Bookstore Column, February 2022, 2)
*5 Kitasato University researchers develop: Green LEDs increase flounder and flatfish growth rate by 1.6 times (Nippon.com, March 2022, 3)
*6 Endo, M. and Takeuchi, S. (2009). Possibility of using deep ocean water for closed circulation aquaculture systems. Deep Ocean Water Research 10 (1) 41-47.
*7 BLUE & GREEN REVOLUTION Home PageThan

Written by: Masato Endo, Associate Professor, Department of Marine Biological Resources, Tokyo University of Marine Science and Technology