The southern rock lobster is a key component of healthy reef ecosystems. They are capable of preying on a range of species, including barren-forming urchins.
They are a long-lived species, with some individuals living for more than 20 years. They live in narrow crevices and cracks in shallow reefs. They are an important commercial fisheries species across southern Australia, forming Victoria’s most valuable commercial fishery.
The southern rock lobster is one of the species which calls Point Addis Marine National Park home. Point Addis Marine National Park is a no-take area, meaning that fishing is not legally permitted. The southern rock lobster is protected within its boundaries.
Deakin University and Parks Victoria recently completed comprehensive monitoring of this Marine Protected Area (MPA). Part of the monitoring program aimed to understand whether there are benefits of "no-take" protection for this species.
They carried out "fisheries independent surveys" both inside and outside of the park. This allowed for comparisons of the number and size of rock lobster found inside and outside marine park boundaries. The surveys involved baiting lobster pots with one kilogram of locally available bait. These were deployed in areas of similar habitat inside and outside Point Addis Marine National Park.
The team captured, counted and determined the sex of southern rock lobsters. They measured the size of all lobsters and assessed the reproductive condition of the females. They created the sampling design in conjunction with local commercial lobster fishers. Having fished there for 20 years, the fishers had much to share about the local area. A total of 240 pots were deployed during this survey, with 120 being placed inside the park and 120 outside.
More and larger individuals were found inside the boundaries of the MPA. Male lobsters were much larger, and females were found in considerably higher abundance inside of the MPA. Over 3.5 times the abundance and 4.5 times the number of rock lobsters above the legal minimum size to be fished were captured within the park. 295 lobsters were caught within the MPA, as opposed to 78 in fished waters. The abundance and weight of lobsters outside the MPA also increased closer to the MPA boundary. This suggests that the park may be positively affecting the lobster supply to surrounding waters open to fishing.
These findings highlight the benefits of no-take marine protected areas for sustaining ecologically and commercially important fisheries species.
The offspring (larvae) of southern rock lobsters spend 12-24 months dispersing through the ocean. Population within the boundaries of Point Addis Marine National Park may act as important sources of new recruits and juveniles. These can replenish populations outside its boundaries and ensure connectivity between distant MPAs.
Parks Victoria's Signs of Healthy Parks (SHP) monitoring program aims to ensure systematic, robust and integrated ecological monitoring across the MPA network. You can read more in their publication An enhanced Signs of Healthy Parks monitoring program for Victoria’s Marine National Parks and Marine Sanctuaries: Point Addis Marine National Park
Dive into the State of the Marine and Coastal Environment 2021 Report, which takes a closer look at the health of Victoria’s marine protected areas.