In recent years, the protection of Croatia’s seas and marine ecosystems has gained increasing attention—but what is actually happening on the ground? Is the network of protected areas enough to preserve the richness of coastal fish communities, or have the rules remained nothing more than words on paper? These questions were at the heart of an online meeting of The Croatian Marine Protected Areas Network on December 9, 2025, which brought together experts, public authorities managing protected areas, and sea enthusiasts. The meeting attracted 62 participants, and the session “Between expectations and reality – assessing the effectiveness and implementation of protection through coastal fish communities” sparked a vital discussion about the effectiveness of Croatian sea protection.
Long-term trends in coastal fish communities
Dr. Nika Stagličić, senior researcher at the Institute of Oceanography and Fisheries in Split, specializing in the ecology of coastal fish and the assessment of management measures, presented findings from long-term monitoring of fish communities in the national parks Brijuni, Kornati, and Mljet. Conducted using non-invasive visual censuses from 2008 to 2023, the research reveals alarming trends: species richness has dropped by roughly a third, and fish abundance has nearly halved compared to unprotected areas 15 years ago.
– At the start of our research, fish biomass inside the parks was significantly higher than in the surrounding unprotected areas. Today, that difference has almost disappeared, – Stagličić noted.
The data also show that fish communities are becoming more homogenized, with smaller average sizes and reduced biomass – particularly for commercially important species – and a chronic lack of large, sexually mature individuals, which are essential for population stability.
Examples of individual species highlight the issue further: the average size of Common two-banded seabream (Diplodus vulgaris) in Brijuni has decreased by 6 cm, while outside the park it remains small but stable at just 17 cm. Normally, this species can grow up to 45 cm. Similar declines have been observed in Striped red mullet (Mullus surmuletus), Brown meagre (Sciaena umbra), and Common dentex (Dentex dentex).
– In just 15 years, instead of improving, or even maintaining, conditions, our parks show clear deterioration. These troubling graphs almost look like an ECG, symbolically showing us that the heart of the sea is failing. Seeing these graphs ‘live,’ underwater, is particularly hard, – Stagličić warned.
Interestingly, the public often blames climate change, which warms the Adriatic and attracts invasive tropical species, for the decline in fish stocks. One particularly problematic invader is the insatiable Bluefish (Pomatomus saltatrix). However, Stagličić stresses that humans bear the primary responsibility: fishing, especially illegal fishing, makes humans the top predator.
Enforcement effectiveness – the main weakness
The main reason marine protection often fails is the lack of compliance and weak enforcement, confirmed Zrinka Jakl, head of the Nature Conservation Department at the Sunce. Her presentation focused on enforcement effectiveness in Croatian marine protected areas.
Jakl emphasized that, despite bans on commercial and small-scale coastal fishing in national parks, fishing continues almost as much as in unprotected areas.
– Current surveillance is marked by inefficiency and a disconnect between the legal framework and its actual implementation. The number of rangers is small, their presence in the field limited, and inspections are poorly equipped and insufficiently motivated, – Jakl explained.
The Analysis of the Institutional and Legal Framework of Existing Capacities in Protected Areas in Croatia, conducted under the one-year Interreg EFFICIENTN2K project, showed that from 2020 to 2022 county authorities recorded just five cases of illegal fishing, seven poaching incidents, and one case of capturing strictly protected animals – even though the problem is clearly widespread. Public institutions managing national and nature parks recorded 29 cases of illegal fishing, zero poaching incidents, and eight cases of capturing strictly protected animals in the same period, referring 23 illegal fishing cases to the competent authorities.
– Looking at the data, it averages to just 1.4 illegal fishing cases per park per year. If there are no fish, and there’s no illegal fishing, so what’s really the problem? – Jakl asked.
Once again, the root of the issue comes back to humans. The problem here is human activity.
‘Beyond ticket sales, the purpose of protected areas is questionable’
The good news is that Croatia’s legal framework is relatively solid. Yet, enforcement still lags behind the needs of nature protection.
– Since Croatia joined the EU, the legal framework has strengthened and capacities in the nature protection sector have gradually improved: for management planning, visitor regulation, stakeholder engagement, and monitoring. The powers of public authorities for marine enforcement have also increased. Yet the Achilles’ heel of the system remains the inefficiency of controlling illegal activities, especially at sea. Without better monitoring and management, the very purpose of protected areas is in question – beyond, of course, collecting entry fees, – Jakl commented.
At nearly every level, political will and accountability are lacking, preventing effective control of crimes against nature for the benefit of society as a whole. Improving enforcement in protected areas and ecological network sites must be a high priority for the Ministry of Environment and Green Transition, as well as other relevant ministries.
Other key recommendations of the Analysis include:
- grant official status and enforcement powers to rangers in ecological network areas and increase fines
- improve legal support and coordination between institutions
- increase personnel and financial resources for surveillance staff
- implement systematic training and knowledge exchange for surveillance personnel
- create national databases on surveillance and enforcement actions in protected areas.
Sea protection must be more than paper
The meeting of The Croatian Marine Protected Areas Network reinforced that protecting the sea should not be just a formality or a PR exercise. Without real action, protected areas risk becoming dead zones, where the richness of the Croatian Adriatic gradually disappears.
– I’m glad we are talking about this issue, because the more it’s discussed, the higher the chances of positive change. At a minimum, awareness of nature protection teaches us that if we leave nature alone, it will be good for us too, – Stagličić said.
What would happen if we truly let nature be? Stagličić explored this question in the article “What prospers in the sea when it’s human-free?”, produced last year as part of the Sunce advocacy campaign And where do you anchor?.